Radio frequency identification (RFID) connected tag communications protocol and related systems and methods

ABSTRACT

Protocols, systems, and methods are disclosed for two or more RFID tags to communicate with each other using direct connections, wherein the two or more RFID tags are configured to mate and directly exchange identification information. A disclosed method includes detecting that a first RFID tag is connected to a second RFID tag. A first message comprising a first tag identification is sent directly from the first RFID tag to the second RFID tag, and the first RFID tag receives a first acknowledgement from the second RFID tag if the first tag identification was correctly received. A second message comprising a second tag identification may be sent directly from the second RFID tag to the first RFID tag and a second acknowledgement may be received from the first RFID tag if the second tag identification was correctly received.

RELATED APPLICATIONS

This application is a continuation-in-part application of co-pendingU.S. patent application Ser. No. 11/590,377 filed Oct. 31, 2006,entitled “Radio Frequency Identification Transponder For CommunicatingCondition Of A Component,” which is incorporated by reference herein itits entirety. The present application is also a continuation-in-partapplication of co-pending U.S. patent application Ser. No. 12/415,343,filed Mar. 31, 2009, entitled “Components, Systems, And Methods ForAssociating Sensor Data With Component Location,” which is incorporatedby reference herein in its entirety.

BACKGROUND

Field of the Disclosure

The technology of the disclosure is related to use of radio frequency(RF) communications, including communications involving RFidentification (RFID) tags or transponders.

Technical Background

It is well known to employ radio frequency (RF) identification (RFID)transponders to identify articles of manufacture. RFID transponders areoften referred to as “RFID tags.” RFID tags are comprised of an antennacoupled to an integrated circuit (IC). An identification number or othercharacteristic is stored in the IC or memory coupled to the IC. Theidentification number can be provided to another system, such as an RFIDreader, to provide identification information for a variety of purposes.For example, if the RFID tag is an active device, the RFID tag includesa transmitter that can transmit the identification. If the RFID tag is apassive or semi-passive device, the RFID tag does not include atransmitter. The passive or semi-passive RFID tag includes a receiverthat receives a wireless RF signal from a transmitter over an antenna,also known as an interrogation signal. The passive or semi-passive RFIDtag wakes up in response to receipt of the interrogation signal and canrespond, including providing identification information, via backscattermodulation communications, as an example.

One application of RFID tags is in communication systems to provideinformation regarding communication components, such as connectors andadapters as examples. In this regard, the communication components areRFID-equipped. An RFID reader can be provided as part of an RFID systemto receive stored information about the RFID-equipped communicationcomponents. The RFID reader can interrogate RFID tags disposed incommunication components in the range of the RFID reader toautomatically discover communication components present in the RFIDsystem. The RFID reader may provide the identification informationregarding the communication components to a host computer system. Thus,it is possible to determine when two particular communication componentsare connected or joined together and when the connection is separated.However, in order for the RFID reader to discover the communicationscomponents present in the RFID system and determine when two particularcommunication components are connected or separated, a significantnumber of unique queries must be performed by the RFID reader and eachof these queries may involve many commands and responses between theRFID reader and the set of RFID tags.

Network equipment may be provided that is configured to supportinterconnections of a number of RFID-equipped communication components.A technician provides the desired interconnections to establishcommunications. If a technician accidentally disconnects an incorrectcommunication component that is RFID-equipped, the host computer systemcan flag an error or provide another indicator to inform the technician,but not before a communication connection is broken. The unintendeddisconnection may result in interruption in communication services andloss of data. Also, connecting the incorrect communication componentstogether can also cause similar issues. An unintended connection betweencommunication components could result in information being exchangedimproperly from one party to another when such exchange is not proper orauthorized.

The same results can occur for other applications in addition tocommunications. For example, if an RFID-equipped power connector isincorrectly disconnected, a host computer system may be able to detectthe disconnection, but not before power is interrupted. If the powerconnector is allowing power to be supplied to a critical device, such asa medical device for example, the interruption of power could be lifethreatening. Another example might be a coupling in a gas or fluiddelivery system where it is critical to know that a connection is madeand made properly. This is true in medical applications where anincorrect connection can cause serious injury or death, in industrialapplications that use various process gases or high pressure hydraulicconnections, and in many other applications where two parts that aredesigned to be mated need to be tracked to ensure that a properconnection exists and/or to provide an indication or alarm when saidconnection has been broken.

SUMMARY OF THE DETAILED DESCRIPTION

Embodiments disclosed in the detailed description include physical andlogical protocols, and related systems and methods, for two or moreradio frequency (RF) identification (RFID) tags to communicate with eachother. One or more RFID tags may communicate with one or more other RFIDtags. Communications can include using direct electrical connections inaddition to standard propagated or reflected field communication viatheir antennas. By communicating using direct electrical connectionsbetween the RFID tags, the amount of time it takes to determineconnectivity between RFID tags is reduced as a result of not having toperform a significant number of unique queries between the RFID tags andan RFID reader, each of which may involve many commands and responsesbetween the RFID reader and the set of RFID tags.

In one embodiment, a system is disclosed that includes a first RFID tagand a second RFID tag, wherein the first and second RFID tags areconfigured to mate to each other and directly exchange information. Forpurposes of this Specification, “directly exchanging” informationbetween RFID tags includes, but is not limited to, one-way or two-wayexchange of information between the RFID tags. In one embodiment, theinformation exchanged between the RFID tags may be general data. Inanother embodiment, the information exchanged may be identificationinformation. In order for the two RFID tags to directly communicate witheach other, an exemplary protocol is disclosed. In one embodiment, theexemplary protocol comprises detecting that a first RFID tag of aplurality of mated RFID tags is connected to a second RFID tag of theplurality of mated RFID tags. A first message comprising a first tagidentification is sent directly from the first RFID tag to the secondRFID tag. The first RFID tag then receives a first acknowledgement fromthe second RFID tag at the first RFID tag if the first tagidentification was correctly received by the second RFID tag. Theprotocol may further comprise the step of sending a second messagecomprising a second tag identification directly from the second RFID tagto the first RFID tag and receiving a second acknowledgement from thefirst RFID tag at the second RFID tag if the second tag identificationwas correctly received by the first RFID tag. The first and second RFIDtags may then continue to directly communicate with each other withoutusing the standard propagated or reflected field communication via theantennas of the RFID tags and without using an RFID reader. In oneembodiment, the communication between the RFID tags is electrical. Inone embodiment, one or both of the RFID tags may be passive RFID tags.If the RFID tags are passive, an RFID reader may be used to providepower to the passive RFID tags.

The embodiments of the direct tag-to-tag communications disclosed hereinallow the ability to transfer multiple bits of information, as opposedto merely asserting a continuous signal. This allows the uniqueidentification associated with each of a plurality of RFID tags to betransferred between the plurality of RFID tags. Since these tagidentifications can be transferred immediately after the connection ismade, the identification of the associated mated RFID tag would alreadybe stored and available to be read by an RFID reader when it detectsthat a new connection has been made. Thus, the RFID reader could simplyperform a direct read of the mated tag identification from the originalRFID tag that was identified as having a new connection. Theconnectivity information of a pair of RFID tags can now be determined byidentifying and reading only one connected RFID tag. This greatlyreduces the amount of communications required between the RFID readerand the set of RFID tags and provides redundancy in the event that onetag of a mated pair is unable to communicate with a reader. The RFIDtags disposed in two communication components can also exchangeidentification information when connected together to provide connectioninformation to the RFID reader when interrogated.

For purposes of this application, the terms “mated RFID tags” and“connected RFID tags” are used interchangeably. As disclosed herein,RFID tags may also be known as RFID transponders and such terms may beused interchangeably. Additional features and advantages will be setforth in the detailed description which follows, and in part will bereadily apparent to those skilled in the art from that description orrecognized by practicing the embodiments as described herein, includingthe detailed description that follows, the claims, as well as theappended drawings.

It is to be understood that both the foregoing general description andthe following detailed description present embodiments, and are intendedto provide an overview or framework for understanding the nature andcharacter of the disclosure. The accompanying drawings are included toprovide a further understanding, and are incorporated into andconstitute a part of this specification. The drawings illustrate variousembodiments, and together with the description serve to explain theprinciples and operation of the concepts disclosed.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a representative schematic view of a plug according to certainembodiments including a condition responsive device operable via a pushbutton;

FIG. 2 is a schematic view of the plug of FIG. 1 as inserted in asocket;

FIG. 3 is a schematic view of a plug as in FIG. 1, wherein the plugdefines an fiber optic connector;

FIG. 4 is a schematic view of an alternate embodiment of a plugincluding an condition responsive device;

FIG. 5 is a schematic view of another alternate embodiment of a plugincluding a condition responsive device, wherein the conditionresponsive device is physically included within the integrated circuitchip of the RFID transponder;

FIG. 6 is a schematic view of another embodiment of a connectorincluding a condition responsive device comprising a push button switch,wherein pushing the button electrically connects and enables the RFIDantenna;

FIG. 7 is a schematic view of yet another embodiment of a connectorincluding a condition responsive device comprising a push button switch,wherein pushing the button electrically disconnects and disables theRFID antenna;

FIG. 8 is a schematic view of still another embodiment of a connectorincluding a condition responsive device, wherein the conditionresponsive device comprises a variable impedance element;

FIG. 9 is a schematic view of an embodiment of a plug having anassociated plug RFID transponder and a socket having an associatedsocket RFID transponder, wherein functionality of the plug RFIDtransponder and/or the socket RFID transponder is effected by insertionof the plug into the socket;

FIG. 10 is a schematic view of another embodiment of a plug having anassociated plug RFID transponder and a socket having an associatedsocket RFID transponder, wherein functionality of the plug RFIDtransponder and/or the socket RFID transponder is effected by insertionof the plug into the socket;

FIG. 11 is a schematic view of yet another embodiment of a plug havingan associated plug RFID integrated circuit chip and a socket having anassociated socket RFID integrated circuit chip and including one RFIDantenna, wherein functionality of the plug RFID transponder and/or thesocket RFID transponder is effected by insertion of the plug into thesocket;

FIG. 12 is a schematic view of another embodiment of a plug having anassociated plug RFID transponder and a socket having an associatedsocket RFID transponder, wherein functionality of the socket RFIDtransponder is effected by insertion of the plug into the socket,further including a contact closure port function;

FIG. 13 is a schematic view of still another embodiment of a plug havingan associated plug RFID transponder and a socket having an associatedsocket RFID transponder, wherein functionality of the socket RFIDtransponder is effected by insertion of the plug into the socket,further including an alternate contact closure port function;

FIG. 14 is a schematic view of another embodiment of a plug having anassociated plug RFID transponder and a socket having an associatedsocket RFID transponder, wherein functionality of the socket RFIDtransponder is effected by insertion of the plug into the socket,further including an alternate bidirectional contact closure portfunction; and

FIG. 15 is a schematic view of one example of a system for mapping fiberoptic connections across a network utilizing RFID transponders.

FIG. 16 is a schematic diagram of an exemplary environment, a connectionmapping system in which radio frequency (RF) identification (RFID) tagsare disposed in connector components and adapter components, in which itmay be desirable for a plurality of RFID tags to be connected andcommunicate with each other;

FIG. 17 is a schematic diagram of exemplary connections betweenintegrated circuits disposed in a connector component connected to anadapter component, each including RFID tags;

FIG. 18 is an exemplary point-to-point configuration in which aplurality of RFID tags may be connected to each other;

FIG. 19 is a generalized flowchart illustrating an exemplary overallprotocol for communicating between a plurality of connected RFID tagsaccording to an exemplary embodiment;

FIG. 20 is a exemplary flowchart illustrating the protocol of FIG. 19 inmore detail, including the exchange of tag identifications between theplurality of connected RFID tags, according to an exemplary embodiment;

FIGS. 21A-21C comprise a flowchart illustrating an exemplary protocolfor communicating between a plurality of connected RFID tags showingvarious steps of an exemplary protocol in response to differentconditions;

FIG. 22 is an alternate exemplary point-to-point configuration in whicha plurality of RFID tags may be connected to each other;

FIG. 23 is an exemplary chain configuration in which a plurality of RFIDtags may be connected to each other;

FIG. 24 is an exemplary ring configuration in which a plurality of RFIDtags may be connected to each other;

FIG. 25 is an exemplary bus configuration in which a plurality of RFIDtags may be connected to each other; and

FIG. 26 is an exemplary star configuration in which a plurality of RFIDtags may be connected to each other.

DETAILED DESCRIPTION

Reference will now be made in detail to the embodiments, examples ofwhich are illustrated in the accompanying drawings, in which some, butnot all embodiments are shown. Indeed, the concepts may be embodied inmany different forms and should not be construed as limiting herein;rather, these embodiments are provided so that this disclosure willsatisfy applicable legal requirements. Whenever possible, like referencenumbers will be used to refer to like components or parts.

Embodiments disclosed in the detailed description include physical andlogical protocols, and related systems and methods, for two or moreradio frequency (RF) identification (RFID) tags to communicate with eachother. Communications can include using direct electrical connections inaddition to standard propagated or reflected field communication viatheir antennas. By communicating using direct electrical connectionsbetween the RFID tags, the amount of time it takes to determineconnectivity between RFID tags is reduced as a result of not having toperform a significant number of unique queries between the RFID tags andan RFID reader, each of which may involve many commands and responsesbetween the RFID reader and the set of RFID tags. The communicationbetween RFID tags can occur without direct control or action on the partof the RFID reader, unlike standard RFID tags which only take action inresponse to a query from an RFID reader.

In one embodiment, a system is disclosed that includes a first passiveRFID tag and a second passive RFID tag, wherein the first and secondRFID tags are configured to mate to each other and directly exchangeinformation. In one embodiment, the information is identificationinformation. In another embodiment, the RFID tags exchange informationelectrically. In order for the two RFID tags to directly communicatewith each other, an exemplary protocol is disclosed. In one embodiment,the exemplary protocol comprises detecting that a first RFID tag of aplurality of mated RFID tags is connected to a second RFID tag of theplurality of mated RFID tags. A first message comprising a first tagidentification is sent directly from the first RFID tag to the secondRFID tag. The first RFID tag then receives a first acknowledgement fromthe second RFID tag at the first RFID tag if the first tagidentification was correctly received by the second RFID tag. Theprotocol may further comprise the step of sending a second messagecomprising a second tag identification directly from the second RFID tagto the first RFID tag and receiving a second acknowledgement from thefirst RFID tag at the second RFID tag if the second tag identificationwas correctly received by the first RFID tag. The first and second RFIDtags may then continue to directly communicate with each other withoutusing the standard propagated or reflected field communication via theantennas of the RFID tags and without using an RFID reader. In oneembodiment, one or both of the RFID tags may be passive RFID tags. Ifthe RFID tags are passive, an RFID reader may be used to provide powerto the passive RFID tags.

In one embodiment, the first and second RFID tags directly exchangeidentification information using a common protocol. In anotherembodiment, the first and second RFID tags are further configured todirectly exchange identification information without using an RFIDreader, other than a source of power if using passive RFID tags.

In certain embodiments, the protocols disclosed herein may be adapted tomultiple (i.e., more than two) RFID tags and may be used for RFID tagsin point-to-point, multi-point, daisy chain, bus, and/or starconfigurations. A direct tag-to-tag connection for communications usingeither passive or active RFID tags is disclosed. One or more RFID tagsphysically connected to each other or a sensor or actuator preferablyhave a protocol to control the exchange of data and control signalsamong the interconnected devices. Several aspects of the protocol aredescribed below. Included are physical layer aspects such asconnector/bus arbitration at the hardware level (tri-state devices andcurrent and voltage mode signaling) as well as higher level logical andapplication layer aspects such as communication initiation and control,multiple-bit protocols, and error detection and correction methods.

The embodiments of the direct tag-to-tag communications disclosed hereinallow the ability to transfer multiple bits of information, as opposedto merely asserting a continuous signal. This allows the uniqueidentification associated with each of a plurality of RFID tags to betransferred between the plurality of RFID tags. Since these tagidentifications can be transferred immediately after the connection ismade, the identification of the associated mated RFID tag would alreadybe stored and available to be read by an RFID reader when it detectsthat a new connection has been made. Thus, the RFID reader could simplyperform a direct read of the mated tag identification from the originalRFID tag that was identified as having a new connection. Theconnectivity information of a pair of RFID tags can now be determined byidentifying and reading only one connected RFID tag. This greatlyreduces the amount of communications required between the RFID readerand the set of RFID tags and provides redundancy in the case that one ofthe mated tags is not accessible to the RFID reader.

Also, the control and communication of devices that do not have nativeRF communications capability can be controlled from the RFID readerusing an RFID tag with physical connections as an intermediary. Examplesof such devices include, but are not limited to, light emitting diodes(LEDs); intelligent actuators (motor controllers, hydraulic controllers,piezoelectric, MEMs); intelligent sensors (pressure, temperature, flow,etc.); intelligent display devices (LCD, electroluminescent, electronicink, etc.); or any electronic device, such as an integrated circuit(IC), a microcontroller, a microprocessor, or an electronic memorydevice. The electronic devices may be programmable in one embodiment. Inaddition, an RFID tag may be easily interfaced to other devices such asswitches, LEDs, various sensors, etc., using the physical levelprotocols described herein.

By employing the disclosed protocols and related systems and methods, asset forth in more detail below in the detailed description andaccompanying Figures, the RFID tag-to-tag connectivity can be determinedwithout the need to burden the RFID reader with extensive communicationbetween two or more RFID tags. Once the connectivity of two or moremated RFID tags is established, the two or more mated RFID tags cancontinue to communicate with each other using direct connections betweenthe RFID tags. In this manner, the two or more mated RFID tags may senda signal, data, or other information between the mated RFID tags.

Before looking at the protocols that mated or connected tags may use tocommunicate with each other or with other devices, a description isgiven of how RFID devices may be used to provide RFID functionality toassociated components, such as telecommunications equipment, whereby theRFID devices can provide a signal indicating a condition relating to theassociated component when interrogated by an RFID reader.

As broadly embodied in FIGS. 1-15 examples of connectors, connectorassemblies, cables, and mapping systems are disclosed, in which RFIDtechnologies are employed, along with one or more condition responsivedevices in certain embodiments. As discussed more fully below, the RFIDtechnologies can be configured in different ways, resulting in differentfunctionalities. In addition, complete RFID transponders and/or portionsof RFID transponders may be located on a plug (such as a connector), asocket (such as an adapter), a housing, a separate object, or othercomponents (or portions thereof). The condition responsive devices areresponsive to one or more conditions and/or change in condition such asa state of contact, electrical contact closure, temperature, pressure,humidity, light, or capacitance (and/or impedance). The conditionresponsive device may be user-operated, for example by pressing a pushbutton or connecting or disconnecting a plug from a socket, or thecondition responsive device may be a passively operated sensor, or bothcould be employed together. Further, the condition and/or change incondition indicated by the condition responsive device may permit orpreclude operation of a given RFID transponder. Alternatively, suchcondition and/or change in condition may simply be registered and/orreported by the RFID transponder without altering the operational statusof the RFID transponder. It should also be understood that elements ofthe embodiments below may be mixed in different ways to achieve stillfurther embodiments and functionality within the scope of the invention.Although the illustrated embodiments are directed to passive RFIDtransponders, further embodiments include one or more active RFIDtransponders depending upon the particular functionality of the RFIDtransponder system desired.

Although the embodiments described herein are directed to RFID systemsused with components of telecommunications equipment, such as fiberoptic connectors and adapters or copper connector and adapters and otherfiber optic and/or copper components, further embodiments are used withnon-telecommunications equipment, particularly regarding components thatinterconnect and/or are exposed to various conditions for which it isdesirable to know the location, connectivity, and/or conditions of thecomponents. The terms plug and socket are generally used herein todefine portions of components that are adapted for connecting to oneanother, such as a connector that is received by an adapter, and are notnecessarily limited to standard plugs and sockets.

FIGS. 1-3 show one example of a plug, such as connector 20, forterminating an optical fiber 22. The plugs of further embodimentsinclude alternative types of connectors such as MT, MJ, RJ, SC, LC,etc., as well as connector fanout assemblies, housings for protectivelysealing the connector-adapter interface, and the like. As shown in FIGS.1-3, fiber 22 is located within an end of cable 24. Fiber 22 isterminated at ferrule 26 located within body 28 of connector 20. Strainrelief 30 is provided at one end of body 28 to protect fiber 22. Cable24 may or may not be pre-connectorized. Connector 20 may be insertedinto a socket, such as adapter 32, within a housing 34. Again, adapter32 and housing 34 are illustrative only, and any type of socket disposedin a component can be employed.

As shown, an RFID transponder 36 is attached to body 28. Therefore, theRFID transponder is associated with the plug. The RFID transponder isassociated with a plug, socket, component, or the like when the RFIDtransponder or a portion thereof, is position on or adjacent to therespective plug, socket, component, or the like such that the RFIDtransponder, when activated, is capable of communicating the identityand/or general location of the associated plug, socket, component, orthe like such that an RFID reader is able to ascertain the identityand/or general location of the associated plug, socket, component, orthe like. The RFID transponder 36 illustrated in FIGS. 1-3 includes anRFID integrated circuit chip 38 and an RFID antenna 40 electricallyconnected by wiring 42. RFID transponder 36 may be in the form of anRFID tag. If desired, RFID transponder 36 may be embedded within body28, or it may be attached to the inside or outside of the body, suchthat the RFID transponder is associated with the connector 20.

Additional wiring 44 electrically connects RFID integrated circuit chip38 to a condition responsive device 46 mounted on or within (as shown)body 28 of connector 20. Condition responsive device 46 is capable ofdetecting at least one condition and/or change of condition andproviding a signal to RFID transponder 36 responsive to the detectedcondition. In some embodiments, RFID transponder 36 and/or conditionresponsive device 46 are selectively activateable and, whenactivateable, may be activated when interrogated by an RFID reader tocommunicate a signal representative of the detected condition. Furtherembodiments comprise RFID transponders and/or condition responsivedevices that are activateable when the associated component is inphysical contact with a technician and/or mating component; while stillfurther embodiments comprise RFID transponders and/or conditionresponsive devices that are continuously activateable.

Activation may be accomplished via an RFID reader (not shown), havingits own RFID circuitry and RFID antenna, which may or may not also belocated on an integrated circuit chip as in RFID transponder 36 of someembodiments. The RFID reader along with an associated database andprocessing element, in accordance with some embodiments, compriseportions of an RFID system for identifying a plurality of components, asdescribed more fully below. The RFID reader and/or its associatedelements may be a separate device from the component that includesadapter 32, such as a handheld RFID reader or an RFID reader disposedsomewhere on the premises within the RFID read range of the componentsbeing monitored, depending on the desired application and functionality.Alternatively, an RFID reader may be located on a housing of acomponent, such as the type in FIG. 2 that holds adapter 32, and may beeither associated with or spaced apart from adapter 32. One RFID reader,whether in a remote housing or associated with the component comprisingthe adapter, may be used to interact with multiple RFID transponders. Itshould be understood that certain aspects are directed to connector andRFID transponder designs alone, for use with one or more RFID readers,while other aspects are directed to the combination of the RFIDtransponder(s), RFID reader(s), and/or components associated with theRFID transponder(s).

RFID integrated circuit chip 38 may include stored information such asserial number, type of connector, cable type, manufacturer,manufacturing date, installation date, location, lot number, performanceparameters (such as attenuation measured during installation),identification of what is at other end of the cable, etc. Suchinformation could be preloaded on RFID integrated circuit chip 38 atmanufacture or upon installation via an RFID reader. Furthermore, theRFID reader, and any associated database and/or processing element, ofcertain embodiments includes stored information relating to one or moreRFID transponder and/or components in order to facilitateidentification, mapping, or other processing of the information receivedfrom one or more RFID transponders. More specifically, the RFID readerincludes information that correlates a unique identification number ofan RFID transponder to a particular plug and/or socket, to a particularcomponent (such as a fiber optic cable assembly with one or moreconnectors), to other portions of the component (such as correlating afirst connector of a fiber optic cable to a second connector, orgrouping multiple adapters of a patch panel, etc.), to past and/orcurrent mating components, and any other parameter, connection,association, or other information that a technician may want know orrecord when working with and/or monitoring the one or more components.

Some embodiments comprise a condition responsive device for detecting acondition relating to the component with which the condition responsivedevice is associated. Condition responsive device 46 of FIGS. 1-3comprises a mechanical switch, or more specifically a push buttonswitch, with two electrical contacts. This exemplary embodiment andother similar embodiments enable the condition responsive device todetect selective physical contact of the component, or more specificallythe plug and/or condition responsive device, by a technician and/or amating component, such as a socket. Alternatively, the conditionresponsive device 46 could be a capacitance or impedance sensor, orother mechanical, electrical, or electromechanical sensors. Asillustrated, condition responsive device 46 is actuated by ahand-operated push button 54, which may be spring loaded, but otheractivation structures such as slides, contact sensors, and the like arealso provided in further embodiments. In alternative embodiments, pushbutton 54 can be activated by contact with housing 34 upon insertion ofconnector 20 into adapter 32. Wiring 44 connects condition responsivedevice 46 to RFID integrated circuit chip 38 to provide informationregarding the condition (such as physical contact by the technician,receipt of the plug into the socket, or the like) detected by thecondition responsive device. For example, certain two-position switchesdefine a condition responsive device that detects and providesinformation regarding the position of the switch. Thus, when activated,RFID transponder 36 would provide information regarding the conditiondetected by the at least one condition responsive device 46 and may alsoprovide other information, such as identification information relatingto the RFID transponder and/or other RFID transponders. A techniciancould identify a given cable/connector by having an RFID reader (notshown) interrogate a panel full of plug RFID transponders associatedwith the connectors and then pressing the button on the givencable/connector, and monitoring the output from the RFID reader to lookfor which cable/connector indicates a certain condition and/or change incondition. Importantly, this could be accomplished if desired withoutotherwise manipulating, plugging, or unplugging the cable/connector,thus preventing undesirable disconnection of services (albeit temporary)to one or more customers. The RFID transponder 36 of FIGS. 1-3 isconfigured and wired to always return a signal to RFID reader,regardless of the condition detected by the condition responsive device,although alternative RFID transponders could be altered to turn on andoff depending on the condition, as discussed below.

In addition, RFID transponder 36 is adapted to communicate with asimilar separate or interrelated RFID transponder or RFID reader (notshown) on housing 34 and/or associated with a respective adapter 32, ifdesired. The ability of the RFID transponders to communicate with oneanother, to store information of two or more RFID transponders, and/orcommunicate with the RFID reader information of two or more RFIDtransponders is discussed more fully below. Furthermore, the RFIDtransponders of alternative embodiments selectively assist a technicianworking with the components associated with the RFID transponders. Forexample, it would be possible to indicate to the technician whichadapter a connector should be received upon the pushing of a button onthe connector. RFID transmission from the RFID transponder(s) or theRFID reader could trigger such indication in various ways.

FIG. 4 shows a modified connector 120 in which condition responsivedevice 146 is activated without a mechanical component such as button 54of FIGS. 1-3. Condition responsive device 146 could thus comprise anintegrated sensor to sense at least one of contact, electrical contactclosure, temperature, pressure, humidity, light exposure, capacitance(and/or impedance), or other environmental condition or parameter. Itmay be more economical to manufacture such a connector 120, wherein themoving parts of a push button are not needed.

The condition responsive device 146 could be configured to detectcontact or other input from a technician, by detecting a temperature orlighting change due to gripping or covering the sensor, shining a lightor laser on it, etc. In such case, condition responsive device 146 couldfunction as above to indicate two alternative conditions. Furtherembodiments include a condition responsive device 146 that functions toindicate a range of conditions corresponding for example to a presentcondition, past condition, past high or low conditions, etc. withreference to temperature, humidity, pressure, etc. Such informationcould be important for detecting and diagnosing problems, and for repairand warranty considerations. Also, such information could be used tocommunicate via RFID transponder 136 that certain equipment should beshut down (for example in case of contact with liquid or overheating isindicated). For certain of such functions, it may be necessary thatcondition responsive device 146 include a power source, either withinthe device itself or externally provided. Also, it may be necessary toinclude additional features on RFID transponder 136 or in RFIDintegrated circuit chip 138 to allow multiple functionalities, such asadding multiple bit capability, analog-digital converters, additionalwiring connectors, etc.

FIG. 5 shows a connector 220 of a further embodiment in which acondition responsive device 246 is part of RFID integrated circuit chip238, again activated without a mechanical component such as button 54 ofFIGS. 1-3. By physically including the condition responsive device 246within the RFID integrated circuit chip 238, the remaining structure issimpler than the structure of FIG. 4, which could provide advantages inmanufacturing or use.

FIG. 6 shows a connector 320 with a condition responsive device 346 thatfunctions to complete an electrical circuit allowing RFID transponder336 to turn on. That is, unless condition responsive device 346 detectsa certain condition, RFID transponder 336 does not operate. Asillustrated, push button 354 is provided for activating conditionresponsive device 346. Therefore, connector 320 could function somewhatlike connector 20, whereby when button 354 is pressed a condition changeoccurs. However, the condition change occurrence is from off to on inFIG. 6, as pressing the push button 354 selectively electricallyconnects the condition responsive device 346 to the RFID integratedcircuit chip 338. FIG. 7 shows another connector 420 with similar butopposite functionality. In connector 420, RFID transponder 436 is onunless it is turned off by the condition responsive device 446, forexample by pressing button 454, which selectively electricallydisconnects the condition responsive device 446 from the RFID integratedcircuit chip 438. Again, the push buttons of FIGS. 1-3, 6, and 7 may behand operated by a technician or actuated upon insertion of the plugsinto the sockets or the like.

It should be understood that use of mechanical condition responsivedevices and push buttons with the embodiments of FIGS. 6 and 7 areoptional. Thus, the more passive condition responsive devices of FIGS. 4and 5 in further embodiments may also be utilized with the connectors ofFIGS. 6 and 7, wherein the RFID transponders are turned on or off bysignals resulting from the condition responsive devices. Also, multiplecondition responsive devices, both passive and active could be employed.For example, pressing a button could actuate one condition responsivedevice to activate an RFID transponder, while a past or presenttemperature condition signal could be obtained from another conditionresponsive device. Still further embodiments include conditionresponsive devices that detect a condition generated by a conditiongenerating device, as described more fully below.

FIG. 8 shows another alternate connector 520 wherein input from ashunted condition responsive device 546 is provided to RFID integratedcircuit chip 538. Condition responsive device 536 could be, for example,a variable impedance element, wherein the condition responsive devicevaries the impedance by changing the resistance or capacitance (and/orinductance) of the condition responsive device. The variable impedanceelement may be placed in parallel with or in series with the leads ofthe RFID antenna 540. Other shunted devices and configurations could beemployed for condition responsive devices of further embodiments.

FIGS. 9-14 show various embodiments in which RFID functionality isachieved or altered when a connector is inserted into an adapter. Insuch fashion, the electrical connections and configurations alsofunction as a condition responsive device, akin to those discussedabove, in which the insertion of a plug into a socket makes theelectrical connection that effects RFID functionality. Further, theplug-in embodiments of FIGS. 9-14 may also be used in conjunction withthe concepts and structures discussed above.

FIG. 9 shows a connector 620 and adapter 632 whereby each includes anRFID transponder 636 and 660. RFID transponder 636 includes an RFIDintegrated circuit chip 638 on connector body 628 and an RFID antenna640 on housing 634. RFID transponder 660 includes an RFID integratedcircuit chip 662 and an RFID antenna 664 on housing 634. Pairs ofcontact points, such as electrical connections 666 a, 668 a, and 670 aon connector 620 mate with connections 666 b, 668 b, and 670 b onhousing 634. The connections 666-670 are located proximate the ferrule626 and adapter 632, although such connections could be located on otherplaces on body 628 and housing 634. Also, to prevent the RFID antennasfrom operating as a monopole when a single contact is made, four sets ofconnections may be used in some embodiments to isolate the antennas.

When connector 620 is received by the adapter 632, electrical contact ismade between connections 666 a and 666 b, 668 a and 668 b, and 670 a and670 b. Thus, the embodiment shown in FIG. 9 effectively operates similarto the embodiment of FIG. 7, wherein the RFID transponders 636 and 660are not functional, unless activated by the receipt of the connector 620into the adapter 632. Functionally, interrogation will show additionalRFID transponders when such connection is made. Also, such structureprovides a double check function to ensure that an inserted connector isproperly received by the adapter. The structure also beneficially doesnot rely for such function on the relative location of the connector andhousing or adapter, which as mentioned above, can lead to inaccurateresults at times in various scenarios.

By placing part of RFID transponder 636 for connector 620 on housing634, space is saved on the connector, which can be useful in somesituations so as to allow for RFID functionality on a relatively smallerconnector. Also, such arrangement leaves more room for other structuresor condition responsive devices on the connector. If desired, theelectrical contacts 670 a and 670 b could be omitted, allowing the RFIDtransponder 660 to be functional at all times. Also, RFID transponder660 could be replaced by a transceiver to provide alternativefunctionality.

FIG. 10 shows a modified version of that shown in FIG. 9, whereinconnector RFID integrated circuit chip 738 and connector RFID antenna740 comprise connector RFID transponder 736 that is associated with theconnector 720. The adapter RFID integrated circuit chip 762 and RFIDantenna 764 comprise adapter RFID transponder 760 associated with theadapter 732 of housing 734. Connections 766 a and 766 b, and 768 a and768 b, respectively, are provided to electronically connect parts of thetwo RFID transponders 736 and 760 so as to render them activateable.Otherwise, connector 720 and adapter 732 are similar to that shown inFIG. 9.

FIG. 11 shows another modification in which RFID transponders 836 and860 share a single RFID antenna 840. A connector RFID integrated circuitchip 838 is associated with the connector 820, and an adapter RFIDintegrated circuit chip 862 is associated with the adapter 832.Connections 866 a and 866 b, and 868 a and 868 b, respectively, provideelectrical contact to complete the activateable connector RFIDtransponder 836 and adapter RFID transponder 860.

FIG. 12 shows yet another embodiment in which connector RFID transponder936 associated with connector 920 and adapter RFID transponder 960associated with adapter 932 of housing 934 are always complete andactive. Therefore, no connections are required to electrically connectRFID integrated circuit chip 938 and RFID antenna 940, or RFIDintegrated circuit chip 962 and RFID antenna 964. However, theconnections 966 a and 966 b may be used to indicate connection of theplug and the socket, in addition to the functionality described below.It should be kept in mind that any of the condition responsive deviceembodiments of FIGS. 1-8 could be used with this embodiment, or anyother, to detect a condition and/or a change in condition of either ofthe RFID transponders.

Adapter RFID transponder 960 associated with the adapter 932 of housing934 includes an electrical contact closure port in communication withRFID integrated circuit chip 962, activated through connections 966 aand 966 b, which come into contact upon insertion of connector 920 intoadapter 932. Therefore, upon insertion of connector 920 into adapter932, the contact closure condition of RFID transponder 960 will change.Interrogating the RFID transponders and looking for a transponderindicating a change in contact closure condition would identify the RFIDtransponder associated with the just-connected adapter. If desired,information regarding the adapter and/or connector could then becommunicated to the reader regarding one or both of the RFIDtransponders and the associated component. It should be understood alsothat the structure and functionality of FIG. 12 could be reversed.Therefore, the RFID transponder in connector 920 could instead includethe contact closure port.

FIG. 13 shows an alternative embodiment in which connector RFIDtransponder 1036 is again entirely located in connector 1020 and adapterRFID transponder 1060 is again entirely located in housing 1034. BothRFID transponders 1036 and 1060 of the embodiment of FIG. 13 areactivateable at all times. Electrical connections 1066 a and 1066 b areprovided to allow for a contact closure input adapter for RFIDintegrated circuit chip 1038. Electrical connections 1068 a and 1068 bprovide a contact closure port output for RFID integrated circuit chip1062. The contact closure ports created by the contacts can communicatewith each other.

This embodiment may or may not rely upon insertion of connector 1020into adapter 1032. Therefore, this embodiment may operate as above,where insertion of the connector closes both contact closure portsgenerating a detectable change of condition signal for both theconnector and adapter. Alternatively, after insertion of all connectors1020 into adapters 1032 within housing 1034, the contact closurecondition of all housing RFID transponders 1060 could be set to a givenvalue (open or closed). Then, the RFID transponder 1060 for a givenadapter could be directed to change its contact closure condition, whichwould be detected by the associated connector RFID transponder 1036,which would change its condition accordingly. Another polling todetermine which connector RFID transponder 1036 had just changed itscondition would provide information as to which two RFID transponders1036 and 1060 in the system were connected. This process could be donethe opposite way (starting with the connectors) if desired. Further,this process could be done serially, adapter-by-adapter orconnector-by-connector, to map an entire equipment panel in fairlyautomated fashion. One advantage to the structure of FIG. 13 and thefunctions made possible thereby are flexibility. Identification can bedone by selectively plugging or unplugging, if desired, or by pollingwithout unplugging or any manipulation of buttons by way of directingcondition changes via a reader or the like.

FIG. 14 shows another connector 1120 and housing 1134 combination of afurther embodiment, wherein the RFID transponders 1136 and 1160 havebi-directional contact closure ports formed by connections 1166 a and1166 b, and 1168 a and 1168 b. Therefore, the RFID integrated circuitchips 1138 and 1162 could be directed to output their identifications tothe other where it would be read and saved, and polling could beconducted to retrieve such information from one or both. In someembodiments, an RFID transponder transfers identification information toone or more other RFID transponders using N bit transfer techniques,wherein one integrated circuit forces contact closure (open or closed) Ntimes at a regular interval to provide bits of data (such asidentification information) to the other integrated circuit(s) thatsenses the forced contact closure. Still further embodiments transferinformation between or among RFID transponders using other electricaltechniques and/or thermal or optical techniques. This approach of RFIDtransponders identifying one another would allow automaticidentification to obtain matching connector and adapter information.RFID integrated circuit chips 1138 and 1162 could require additionalpower and additional bi-directional communication and sensingfunctionality. Again, this approach allows cataloging of an entire panelof connections without plugging or unplugging, or the manipulating ofbuttons or the like.

FIG. 15 shows one representative example of a system incorporatingcertain features of the connectors disclosed above to allow mappingfiber optic cable connections utilizing RFID functions. Variousembodiments provide for mapping of the physical location of thecomponents associated with the RFID transponders and/or mapping of theconnectivity of the components associated with the RFID transponders.Referring again to FIG. 15, as schematically illustrated, system 1200includes a housing 1202, a reader 1204 and a fiber optic cable 1206.Each end of fiber optic cable 1206 includes a connector 1208(1),1208(2). Other examples of connectors 1208(3)-1208(18) are furtherdescribed below. For simplicity of illustration, housing 1202 is shownto include one adapter 1210(1) that receives one connector 1208(1).However, housing 1202 may have a plurality of such adapters forreceiving a plurality of connectors. Housing 1202 may comprise anyelement along a fiber optic cable network, such as a router, server, anyconnected device, wireless device, patch panel, adapter, or even anotherconnector, etc. Therefore, any device to which a fiber optic cable maybe attached could comprise housing 1202.

Each connector 1208 has an associated RFID transponder (not visible inFIG. 15). The RFID transponder may be one of the types discussed above.Thus, the RFID transponders may be entirely or partially located on theconnectors. Also, a condition responsive device for detecting acondition and/or change of condition and communicating it to the RFIDtransponders may also be included. The condition responsive device mayinclude electrical connections, a push button operated device, contactclosure structures, or other structures for detecting insertion of aconnector plug into an adapter. The adapter may also include an RFIDtransponder for receiving signals from a condition responsive device andtransmitting signals related to the detected condition. Therefore, uponreceipt of a connector 1208 into an adapter 1210, a change in conditionis registered via one or more of the structures or functions describedabove. A polling of RFID transponders before and after such insertion,or via sending contact closure instructions and re-polling, willidentify which connector and/or adapter have been connected. Informationwithin the inserted connector, in this case 1208(1), will also identifythat connector 1208(2) is or should be at the opposite end of fiberoptic cable 1206. This information may be made available to thetechnician, for example for connecting connector 1208(2) to a particularadapter, for connectorizing the cable, etc.

This mapping functionality may be extended. For example, connector1208(2) may further be received by an adapter 1210(2) in another housing1212, which may be a patch panel or adapter. Again, a conditionresponsive device may detect insertion, which can be reported in variousways to reader 1204. Housing 1212 may have another adapter 1210(3) forreceiving another connector 1208(3), and the process may continuefurther, insertion of connector 1208(3) bringing forth identification ofconnector 1208(4) at the other end of fiber optic cable 1214.

The information can be flexibly managed in various ways, as desired. Forexample, adapters 1210(2) and 1210(3) may be considered a single adapterconnecting two connectors 1208(2) and 1208(3), if desired. Also,internal cabling (not shown) could connect adapters 1210(2) and 1210(3),for example as on the inside of a patch panel housing or the like. Theinternal cabling could include RFID functionality, for example byconnecting to connectors 1208(2) and 1208(3) directly or via adaptorshaving structure for detecting or communicating change of condition, asdescribed above. Alternatively, a database could hold informationregarding which adapters are internally connected within a patch panelby correlating the unique identifications of the respective adapters,and RFID functionality could be employed with the connectors andadapters only.

Cables having different types and numbers of connectors at each end canemploy RFID functionality as well. For example, as illustrated, fiberoptic cable 1216 comprises a break-out for twelve individual opticalfibers. The break-out may also be referred to as a fiber optic fanoutassembly. Connectors 1208(5) through 1208(16) (not all shown) eachterminate one of the fibers, whereas connector 1208(17) is a multifiberconnector. Connector 1208(4) is connected to connector 1208(16), eitherdirectly or via an adapter, such as adapter 1210(4). Fiber optic cable1218 is another twelve-fiber cable having a multifiber connector1210(18). Each of the connectors and adapters may include RFIDtransponders, as discussed above, that are associated with conditionresponsive devices for detecting a condition such as insertion. Also,the RFID transponder on each connector on a cable may be provided at themanufacturing plant and/or in the field with information regarding theother connector or connectors attached to that cable. In addition oralternatively, the RFID transponders may be able to communicate with oneanother to identify one another and store in memory (preferably in theintegrated circuit chip) the identity of the other RFID transponder forsubsequent communication with an RFID reader, for example, using the Nbit transfer described above with respect to the embodiment of FIG. 14.Therefore, plugging in one end of a cable provides some information viathe RFID transponder as to the other end of the cable and/or fiber. Itshould be understood that any number of fibers could be employed withina cable, and any number of break-outs from the multifiber cable could beemployed. Also, a multifiber cable with multifiber connectors at eachend could be employed.

It should be kept in mind for purposes of the present disclosure, that aconnector connecting directly to other components or another connector(rather than to a patch panel adapter per se, or the like) may beconsidered an adapter and housing into which the connector is connected.Therefore, the benefits described herein may be recognized when twoconnectors are connected together, with or without an adapter, and oneof the connectors or the adapter would therefore be considered the“adapter” for the other connector in that situation. Thus, in somescenarios, the element to which the connector connects would beconsidered the “adapter” for purposes of this disclosure.

The RFID transponders for multifiber cables may hold additionalinformation, such as fiber order and polarity. If the multifiberconnectors include information regarding the ordering of fibers withinthe multifiber connectors, the functionality can be improved by mappingout with more certainty the communication path throughout the system.Such mapping may include mapping the physical location, theconnectivity, and/or other parameters relating to the various components

Such a system 1200 can employ a second reader 1220 if desired. Reader1220 could be a handheld reader used by a technician. In addition oralternatively, reader 1220 could be a second fixed reader (such asreader 1204), so that the range of system 1200 can be extended over awider area than by using reader 1204 alone. If desired, a database 1222may be stored in a general or special purpose computer, connected toreaders 1204 and 1220 either wirelessly and/or by hard-wiring. Database1222 can maintain various records as discussed above, including recordsof connector/adapter connections, RFID interrogations and responses,past and present conditions, and changes of condition, etc.

The use of condition responsive devices to indicate a change ofcondition such as plug insertion, possibly in combination with catalogedinformation regarding connector identification by fiber optic cableand/or fiber ordering, can provide various levels of detail andfunctionality for installing, servicing, or altering a network. It istherefore possible, using the teachings above, to create a network thatessentially self-maps itself upon insertion and/or pressing of buttonsor other activation of condition responsive devices. Also, such systembeneficially does not depend only on proximity of RFID transponders inconnectors and adapters, although such functionality could be utilizedwithin a part of such system if desired.

Referring again to the embodiments disclosed herein that comprisecondition responsive devices, still further embodiments comprisecondition generating devices that are associated with one or morecomponents (and/or the plug or socket of the respective component) andthat are adapted to generate the condition sensed by the conditionresponsive device. Exemplary embodiments include the systems illustratedin FIGS. 9-14, wherein one of the connector RFID transponder and theadapter RFID transponder includes a condition responsive device and theother RFID transponder comprises a condition generating device. Thecondition generating device of various embodiments generates thecondition when a certain event occurs, for example when the plug isinserted into the socket, when the RFID transponder comprising thecondition generating device is communicated with by the RFID reader toinstruct the generation of the condition, and/or when similar eventsoccur, such that the condition responsive device is able to detect thecondition. The condition generated by the condition generating devicemay be of any form, non-limiting examples include an electric currentvia an electrical connection, a predetermined RF signal, visualindications, audible indications, or similar conditions. In someembodiments, the plug must be at least partially received by the socketin order for the condition responsive device to detect the generatedcondition, whereas in other embodiments the two components with whichthe condition responsive and condition generating devices are associatedneed not be in physical contact and/or within a certain distance of oneanother. The condition generating device of the embodiment of FIG. 14forces the contact closure that is detected by the condition responsivedevice (portion of the integrated circuit) of the other RFID transponderto enable the RFID transponder with the condition responsive device toreceive information via the N bit transfer from the RFID transponderwith the condition generating device. Use of the condition generatingdevice and condition responsive device enable two RFID transponders tocommunicate with one another in order to correlate the two components,to transfer and/or store identification information about one another,and/or to perform other functions desired by the technician.

As described above with reference to FIG. 15, one component may comprisetwo or more RFID transponders associated with various portions of thecomponent, such as, for example, a fiber optic drop cable with two ormore connectors wherein each connector comprises an associated RFIDtransponder. In some embodiments, each of the RFID transpondersassociated with the component includes identification information of theother RFID transponders and/or the portions of the component associatedwith the RFID transponders. In such embodiments, communication with oneof the RFID transponders may enable an RFID reader to receiveinformation, such as identification information and the like, about morethan one RFID transponder to improve the performance of the RFID system.In additional embodiments, the RFID transponders of separate components(or the same component) are adapted to communicate with one another inorder to allow information of each of the RFID transponders to becommunicated to an RFID reader via communication with only one RFIDtransponder. In certain of these additional embodiments, the integratedcircuit chip of the RFID transponder comprises a memory into which maybe stored identification information of other RFID transponders and fromwhich such additional identification information may be retrieved toprovide to an RFID reader and/or other RFID transponders. The memory ofcertain embodiments may permanently retain information, may deleteinformation at predetermined intervals, may delete information whencommanded, and/or may delete information upon occurrence of a particularevent, such as disconnecting the plug from the socket, to list onenon-limiting example.

In view of the above, it is apparent that many modifications andre-combinations of the above embodiments or their components may bedone. Connectors, adapters, cables including connectors, connectionscomprising a connector and adapter, and mapping systems may include someor multiple of the above features and functionality. One or morecondition responsive devices can detect differences in condition.Communication of the detected conditions, either by or between RFIDtransponders, can provide useful information for identifying or mappingone or more connectors, cables or connections, including mapping allconnections on a single panel or across a network. Reliance onalternative systems requiring relative proximity RFID function is notnecessary, as detected conditions of one sort or another provideinformation. Changes in condition brought about by insertion of aconnector into an adapter can be designed with connector tolerances thatmake the resulting information more accurate than proximity-basedsystems as well, thereby reducing or eliminating false positives.Further, such change-of-condition based systems allow for panels toefficiently include more connections, more tightly spaced. Also, pastand present condition information can be stored for later RFIDcommunication for various functions and purposes. If desired some, mostor substantially all of the RFID transponder hardware may be located onthe connector or housing, depending on the desired application, the needfor additional connections, power, etc.

It may be desirable when a plurality of RFID tags may be connected, asin the environments described above, that the RFID tags may communicatedirectly with each other or with one or more other devices. By employingthe disclosed protocols and related systems and methods, as set forth inmore detail below in the detailed description and accompanying Figures,the RFID tag-to-tag connectivity can be determined without the need toburden the RFID reader with extensive communication between two or moreRFID tags. Once the connectivity of two or more mated RFID tags isestablished, the two or more mated RFID tags can continue to communicatewith each other using direct connections between the RFID tags. In thismanner, the two or more mated RFID tags may send a signal, data, orother information between the mated RFID tags.

FIG. 16 is a schematic diagram of an exemplary environment in which aplurality of RFID tags may be connected, where it is desirable for aplurality of RFID tags to communicate with each other. FIG. 16illustrates an exemplary embodiment of a component mating system 1310where an RFID tag 1312 of a first connector 1314 is in electricalcommunication with an RFID tag 1316 of a second connector 1318 tofurther describe possible information exchanges between the two,including identification information. Note that although FIG. 16 isdiscussed with respect to RFID tag 1312 and RFID tag 1316, the RFID tags1312 and 1316 could be positioned on a device. In addition, a devicethat emulates an RFID tag could be used in place of RFID tags 1312 and1316. In one embodiment, a device 1312 and a device 1316 could be usedin the place of RFID tag 1312 and RFID tag 1316 and the two devices cancommunicate with each other in the same manner as the RFID tag 1312 andthe RFID tag 1316 communicate with each other, as described in moredetail below.

The RFID tags 1312 and/or 1316 can be configured to allow the mating ordemating of the first connector 1314 to and/or from the second connector1318. The first connector 1314 may include a body 1315 adapted to bemated to a body 1317 of the second connector 1318. The second connector1318 in this example includes an internal chamber 1319 disposed in thebody 1317 of the second connector 1318 that includes a geometryconfigured to receive a complementary, fitted geometry of the body 1315of the first connector 1314. The mating or demating may be based on theidentification information provided by the first connector 1314 to thesecond connector 1318, or vice versa, or based on identificationinformation exchanges between both the first and second connectors 1314,1318, although not required. The mating or demating may also be based onlack of receiving identification information provided by the firstconnector 1314 to the second connector 1318, or vice versa. The RFIDtags 1312, 1316 may perform processing to determine if the connectors1314, 1318 should be mated or demated, or such processing may beperformed by an RFID reader system 1320 or other system. The RFID readersystem 1320 or other system may be able to wirelessly communicate withone or more of the RFID tags 1312, 1316 to receive the identificationinformation as an example. The mating or demating of the connectors1314, 1318 may be based on whether the identification information isdeemed proper according to defined criteria or connection configurationsdesired.

In this regard, as illustrated in the example in FIG. 16, the firstconnector 1314 is mated to the second connector 1318. The integratedcircuit (IC) chips 1322, 1324 of the first and second connectors 1314,1318 each include memory 1326, 1328 that have stored identificationinformation regarding the IC chips 1322, 1324. Thus, this identificationinformation can be used to identify the first IC chip 1322 distinctlyfrom the second IC chip 1324, and thus the first connector 1324distinctly from the second connector 1318. The identificationinformation can be communicated to an RFID reader 1330 provided as partof the RFID reader system 1320.

In one embodiment, the RFID tags 1312, 1316 are passive devices. PassiveRFID devices do not require their own power sources. When the RFID tags1312, 1316 in this embodiment are passive tags, the IC chips 1322, 1324may be powered from RF energy harvested or received from the RFID reader1330 through antennas 1334, 1336 coupled to the IC chips 1322, 1324.Power can be harvested from an interrogation signal 1332 transmitted bythe RFID reader 1330 in the RFID reader system 1320 and received by theantennas 1334, 1336. Thus, passive RFID devices may be desired whenproviding a power supply is not desired or otherwise impractical due tocost or size limitations. The antennas 1334, 1336 may be any type ofantenna that is tuned to the desired reception and/or transmissionfrequency(s), including but not limited to a dipole and monopoleantenna. The antennas 1334, 1336 can be external to or integrated in theIC chips 1322, 1324.

The IC chips 1322, 1324 enable certain functionality and communicationfor the RFID tags 1312, 1316. In this regard, capacitors 1335, 1337 maybe communicatively coupled to the IC chips 1322, 1324 to store excessenergy received through the antennas 1334, 1336 for providing power tothe IC chips 1322, 1324 when the antennas 1334, 1336 are not receivingan RF signal from an RFID reader and/or to supplement such power duringtimes when power demand may be greater than harvested through theantennas 1334, 1336. Note that the RFID tags 1312, 1316 could also besemi-passive or active devices. A semi-passive RFID tag may include apower source to assist in powering the RFID tag. An active RFID tagincludes a power source and a transmitter.

Also in this embodiment, both the first connector 1314 and the secondconnector 1318 provide interfaces 1338 and 1340, respectively, thatcontain one or more electrical leads 1342, 1344 each coupled to theirrespective IC chips 1322, 1324. The electrical leads 1342, 1344 aredesigned to come into direct contact with each other when the firstconnector 1314 is mated to the second connector 1318 in this embodimentto form a wired connection, as illustrated in FIG. 16. When theelectrical leads 1342, 1344 come into direct electrical contact in thisembodiment with each other as a result of the connection, a connectionevent occurs. In response, the IC chips 1322, 1324 of the first andsecond connectors 1314, 1318, respectively, initiate communications witheach other over the electrical leads 1342, 1344. Contact other thandirect ohmic contact between the electrical leads 1342, 1344 is alsopossible, including capacitive and inductive coupling.

Identification information regarding the identity of the first connector1314 and the second connector 1318 stored in memory 1326, 1328,respectively, can be exchanged and stored to signify the connection ofthe first connector 1314 to the second connector 1318. Similarly, lackof exchange of identification information can be used to signify thelack of connection between the first connector 1314 and the secondconnector 1318. Thus, for example, if the IC chip 1322 in the firstconnector 1314 receives and stores an identification of the IC chip 1324in the second connector 1318, it can be determined by the RFID reader1330 interrogating the IC chip 1322 in the first connector 1314 that thefirst connector 1314 is mated with the second connector 1318. The sameis possible in vice versa—the RFID reader 1330 can interrogate thesecond connector 1318 and identification information stored in the ICchip 1324 regarding the identification information of the IC chip 1322can be used to determine if the second connector 1318 is mated with thefirst connector 1314. Lack of identification information exchangedbetween the first connector 1314 and the second connector 1318 can beused to indicate to the first connector 1314 and/or the RFID reader 1330that the first connector 1314 is not mated with the second connector1318. In an alternate embodiment, discussed more fully below, each ofthe RFID tags 1312, 1316 may determine that it is mated with one or moreof the other RFID tags without using the RFID reader 1330.

Either one or both of the first connector 1314 and the second connector1318, or either one or both of the first RFID tag 1312 and the secondRFID tag 1316, can also communicate their own identification informationas well as exchange identification information with the other connector1318, 1314, respectively, as well as the RFID reader 1330. The first andsecond connectors 1314, 1318, or either one or both of the first RFIDtag 1312 and the second RFID tag 1316, may communicate other informationstored in memory, such as serial number, type of connector, cable type,manufacturer, manufacturing date, installation date, location, lotnumber, performance parameters (such as attenuation measured duringinstallation), identification of what is at other end of the cable, etc.Such information could be preloaded in the memory 1326, 1328 of the RFIDtags 1312, 1316 at manufacture or upon installation via the RFID reader1330.

The RFID reader system 1320 coupled to the RFID reader 1330 may beconfigured to receive identification information pairs signifying thefirst connector 1314 mated to the second connector 1318 within the rangeof the RFID reader 1330. This information may be stored in a database1346 provided in the RFID reader system 1320 processed in a componentmanagement system 1348, as illustrated in FIG. 16. The componentmanagement system 1348 may include control systems and related softwarefor processing the information received from the first and secondconnectors 1314, 1318 to perform a number of tasks. These tasks include,but are not limited to, recording the identification information pairs,providing identification information pairs information to a technician,recording which connectors are not mated, and providing othertroubleshooting and diagnostic information, as will be described ingreater detail below. The processing may include decision-making onwhether to communicate to one or both of the RFID tags 1312, 1316 toprovide instructions to cause the RFID tags 1312, 1316 to allow matingor demating of the components with which the RFID tags 1312, 1316 areassociated, based on the identification information. Furthermore, thecomponent management system 1348, and any associated database 1346and/or processing element, includes stored information relating to oneor more RFID tags in order to facilitate identification, mapping, orother processing of the information received from one or more RFID tags.More specifically, the RFID reader 1330 includes information thatcorrelates a unique identification number of an RFID tag 1312, 1314 tothe first and second connectors 1314, 1318, respectively, and to anyother parameter, connection, association, or other information that atechnician may want to know or record when working with and/ormonitoring the first and second connectors 1314, 1318.

To provide further detail regarding how the IC chips 1322, 1324 in theRFID tags 1312, 1316 may be communicatively coupled together by example,FIG. 17 is provided. FIG. 17 illustrates more detail on an exemplarychip and pin layout of exemplary IC chips 1322, 1324 of the RFID tags1312, 1316 of the component mating system 1210 in FIG. 16. The IC chips1322, 1324 are electrically and communicatively coupled to each otherwhen their respective first connector 1314 and second connector 1318 aremated. The IC chips 1322, 1324 of the RFID tags 1312, 1316 are coupledtogether when connections are made between the first and secondconnectors 1314, 1318.

Each IC chip 1322, 1324 in this embodiment contains RF inputs in theform of RF input pins 1350, 1352. The antennas 1334, 1336 (FIG. 16)coupled to the IC chips 1322, 1324 are configured to receive RFcommunication signals from the RFID reader 1330 (FIG. 16) via the RFinput pins 1350, 1352. Note that the RF input pins 1350, 1352 can alsosupport any type of antenna, including dipole antenna, monopole antenna,loop antenna, or any other type of antenna. An antenna coupled to the RFinput pins 1350, 1352 may be configured to operate at any frequencydesired, including 2.4 GigaHertz (GHz) and 900 MegaHertz (MHz), asexamples.

As further illustrated in FIG. 17, the RFID-enabled IC chips 1322, 1324can be designed to be coupled in a point-to-point fashion. Ground iscoupled together for each IC chip 1322, 24 when a connection isestablished by coupling ground pins 1354, 1356 of the IC chips 1322,1324 together via a ground line 1358. One or more capacitors 1360 may becoupled between PWR and GND to provide energy storage of power receivedfrom RF communication signals to allow the IC chip 1322 to operate whennot being energized by an RF communication signal. Also as illustratedin FIG. 17, the IC chips 1322, 1324 are configured to communicate witheach other over a serial communication line 1362. Each IC chip 1322,1324 contains at least one communication pin 1364, 1366. Eachcommunication pin 1364, 1366 allows serial communications to and fromthe IC chips 1322, 1324. Additional IC chips, as part of additional RFtags not shown in FIG. 17, could be connected together in a daisy-chainfashion (as shown in FIG. 23 below) and communicatively coupled to eachother if a second communication pin is provided in the IC chip.

A capacitor bank 1378 may also be provided in the RFID tag 1316 to becharged during interrogation by the RFID reader 1330 and to providereserve power when not being interrogated by the RFID reader 1330 orwhen energy from the RFID reader 1330 is sporadic or otherwise notstrong enough to power the second connector 1318.

It is noted that FIGS. 16 and 17 are illustrative environments only andthat there may be other environments or settings in which RFID tags maybe connected or mated to each other. For example, if an RFID-equippedpower connector is incorrectly disconnected, a host computer system maybe able to detect the disconnection, but not before power isinterrupted. If the power connector is allowing power to be supplied toa critical device, such as a medical device for example, theinterruption of power could be life threatening. Another example mightbe a coupling in a gas or fluid delivery system where it is critical toknow that a connection is made and made properly. This is true inmedical applications where an incorrect connection can cause seriousinjury or death, in industrial applications that use various processgases or high pressure hydraulic connections, and in many otherapplications where two parts that are designed to be mated need to betracked to ensure that a proper connection exists and/or to provide anindication or alarm when said connection has been broken. The tagcommunications disclosed herein may also be used in environments thatinclude, but are not limited to, the above examples, as well asenvironments involving industrial controls, apparel, consumerelectronics, machinery, sensor systems, electrical interconnects, fluidcouplings, beverage dispensing, security authentication, and lockablecontainers. In fact, the tag communications disclosed herein may beapplied anywhere that two mated parts need to be identified to managetheir connection or disconnection.

In addition, in certain embodiments, multiple RFID tags may be connectedto each other via a variety of means (including but not limited toohmic, inductive, and capacitive connections) and configurations(including but not limited to point-to-point, bus, ring, and starconfigurations). FIGS. 18 and 22-26 show a representative sample of someof these configurations. These figures do not show all possibleconnection means, topologies or combinations of connection means andtopologies, but are simply a representative sample.

FIG. 18 shows two RFID tags 1312, 1316 in an exemplary point-to-pointconfiguration. Note that although FIG. 18 is discussed with respect toRFID tag 1312 and RFID tag 1316, the RFID tags 1312 and 1316 could bepositioned on a device. In addition, a device that emulates an RFID tagcould be used in place of RFID tags 1312 and 1316. In one embodiment, adevice 1312 and a device 1316 could be used in the place of RFID tag1312 and RFID tag 1316 and the two devices can communicate with eachother in the same manner as the RFID tag 1312 and the RFID tag 1316communicate with each other, as described in more detail below.

The two RFID tags 1312, 1316 are connected by a common line 1380. Thetwo RFID tags 1312, 1316 may be connected to each other via a variety ofmeans (including but not limited to ohmic, inductive, and capacitiveconnections). In the embodiment of FIG. 18, a shared bidirectionalsignal line 1382 also connects the two RFID tags 1312, 1316. In analternate embodiment, as seen below in FIG. 22, two signal lines areused, each being unidirectional. A shared bidirectional line may offereconomy of hardware (ports, circuit traces, etc.) but may require moresophisticated electronics and protocols. The alternate embodiment havingtwo unidirectional signal lines may utilize simpler electronics, but mayuse more costly interconnect hardware. Each of the variousconfigurations of connected RFID tags disclosed herein can use either ashared bidirectional signal line or two or more unidirectional signallines.

In order to determine connectivity between one or more tags such as theRFID tags 1312, 1316 in FIG. 18, some information needs to betransferred between the RFID tags 1312, 1316. In general, the actualnature of the physical signals shared between the tags is irrelevant andcould function via a variety of approaches. It is possible to determineconnectivity via an RFID reader (such as the RFID reader 1330 in FIG.16) and a set of tags (such as the RFID tags 1312, 1316) with even themost simplistic tag-to-tag communication mechanism; i.e., a continuoussignal that can be asserted or de-asserted by one tag upon command fromthe reader and sensed by the mating tag when it is connected. Thefollowing is an example of how connectivity may be determined pursuantto a known procedure.

An RFID reader (such as the RFID reader 1330 in FIG. 16) can query a setof tags (such as the RFID tags 1312, 1316) looking for any newconnections. Note that additional RFID tags besides the RFID tags 1312,1316 may exist in any potential set of mated RFID tags. If one of theRFID tags 1312 or 1316 is identified with a new connection, the RFIDreader 1330 can ask that RFID tag 1312, 1316 to assert its “connectivitysignal.” The RFID reader 1330 can then perform a query to the entire setof RFID tags looking for the single RFID tag that now can sense a“connectivity signal” from its mating RFID tag. Once the mated RFID tagresponds, the RFID reader 1330 knows the two RFID tags that were justconnected. Note, that to complete this query, the RFID reader 1330 hasto issue a command so that the original RFID tag de-asserts itsconnectivity signal in preparation for the next set of queries that theRFID reader 1330 will have to perform. Also note that in order for theRFID reader 1330 to determine connectivity in this previous example, asignificant number of unique queries must be performed and each of thesequeries may involve many Electronic Product Code Generation 2 (EPC Gen2) commands and responses between the RFID reader 1330 and the set ofRFID tags. In order to reduce the amount of time it takes for an RFIDreader to determine connectivity between RFID tags, it is much moreefficient to consider a more optimum approach, such as the embodimentsand protocols disclosed herein.

The embodiments of the direct tag-to-tag communications disclosed hereinallow the ability to transfer multiple bits of information, as opposedto merely asserting a continuous signal. This allows the uniqueidentification associated with each of the RFID tags 1312, 1316 (orother potentially connected RFID tag) to be transferred between the twoRFID tags 1312, 1316. Since these tag identifications can be transferredimmediately after the connection is made, the identification of theassociated mated RFID tag would already be stored and available to beread by the RFID reader 1330 when it detects that a new connection hasbeen made. Thus, the RFID reader 1330 could simply perform a direct readof the mated tag identification from the original RFID tag that wasidentified as having a new connection. The connectivity information of apair of RFID tags (such as RFID tags 1312, 1316) can now be determinedby identifying and reading only one connected RFID tag. This greatlyreduces the amount of communications required between the RFID reader1330 and the set of RFID tags and provides redundancy in the case thatone of the mated tags is not accessible to the RFID reader.

For the direct tag-to-tag communications embodiments disclosed herein,some type of protocol initiation method is required for the RFID tags1312, 1316 to initiate the transfer of tag identifications. In oneembodiment, each of the RFID tags 1312, 1316 is configured to directlyexchange identification information using a common protocol, i.e., bothRFID tags 1312, 1316 will use the same protocol to determineconnectivity between the RFID tags 1312, 1316 and will use the sameprotocol to communicate between the connected RFID tags 1312, 1316.

FIG. 19 is a generalized flowchart illustrating an exemplary overallprotocol for determining connectivity and communicating between aplurality of connected RFID tags according to an exemplary embodiment.The protocol starts at block 1384. A signal may be asserted orde-asserted by one of the RFID tags 1312, 1316. In one embodiment, thissignal may be asserted or de-asserted upon command from the RFID reader1330. At block 1386, when the signal is sensed by one of the RFID tags132, 1316, a connected tag is determined to be initiating a datatransfer. This step in block 1386 may be performed electrically by theRFID tags 1312, 1316 prior to the initiation of the communicationsprotocol. Once a connection between the RFID tags 1312, 1316 isdetected, the RFID tags 1312, 1316 may then exchange tag identifications(block 1388). The information in the connected RFID tags 1312, 1316 maybe used (block 1390) for any purpose for which they are suited. Theinformation in the RFID tags may be accessed by the RFID reader at anytime and may be used at any time. Once the connected tag identificationsare exchanged, the tag identifications may also be used for any suitablepurpose. This would include the use of the connected tag identities forany purpose, such as, but not limited to, communicating a connectionevent or the mated tag identities to a RFID reader. In anothernon-limiting embodiment, the mated RFID tags 1312, 1316 may be used toprovide information regarding communication components, such asconnectors and adapters as examples, in order to automatically discovercommunication components present in the RFID system and to determinewhen two particular communication components are connected or joinedtogether and when the connection is separated. This information can beprovided and used at any time, before or after the exchange of tagidentifications. At some point, a disconnect of one of the mated RFIDtags 1312, 1316 may be detected (block 1392). At this point, the methodreturns to the start and looks to detect another mated RFID tag. In oneembodiment, the mated tag identity may be cleared and that informationmay be used for the RFID reader to determine that the RFID tags are nolonger connected, or to determine a status of the RFID tags. In thisregard, the term “disconnect” may include, but is not limited to, theact of unconnecting an RFID tag or other device. A RFID tag that is notconnected may be referred to as in a state of disconnect.

FIG. 20 is an exemplary flowchart illustrating the protocol of FIG. 19in more detail, including the exchange of tag identifications betweenthe plurality of connected RFID tags, according to an exemplaryembodiment. In FIG. 20, the protocol starts at block 1394. A signal maybe asserted or de-asserted by one of the RFID tags 1312, 1316. In oneembodiment, this signal may be asserted or de-asserted upon command fromthe RFID reader 1330. At block 1396, when the signal is sensed by one ofthe RFID tags 1312, 1316, a connected tag is detected. Steps are thentaken at block 1398 to assure the availability of a communicationschannel between RFID tags 1312, 1316. Standard methods of contentionresolution can be applied to assure availability of the communicationschannel.

Once the availability of a communications channel is assured, at block1400, a tag identification of a first RFID tag of the RFID tags 1312,1316 is sent in a first message to the second RFID tag of the RFID tags1312, 1316. In one embodiment, the first message may be sent from thefirst RFID tag to the second RFID tag over a shared connection, such asthe signal line 1382 in FIG. 18. In one embodiment, the first messagemay also include an error detection code. Once the first message withthe tag identification of the first RFID tag is received by the secondRFID tag of the connected RFID tags, the second RFID tag will check tosee if the tag identification was correctly received. In one embodiment,an error detection code sent in the first message may be used todetermine if the tag identification of the first RFID tag was correctlyreceived by the second RFID tag. If the tag identification was correctlyreceived, the second RFID tag will send an acknowledgement to the firstmated RFID tag to indicate that the tag identification was correctlyreceived (block 1402). If the tag identification was not correctlyreceived (i.e., an acknowledgement is not received), then the tagidentification may be retransmitted up to a certain number of times. Ifthe tag identification is not correctly received after a certain numberof retransmissions, an error code may be entered in a memory of the RFIDtag and the process continues in one embodiment. In another embodiment,the connected tag identification may be deleted so that a mistake is notmade by reading erroneous information by the RFID reader.

In the embodiment of FIG. 20, the second RFID tag will then send asecond message including its tag identification to the first RFID tag ofthe connected RFID tags (block 1404). In one embodiment, the secondmessage may be sent from the second RFID tag to the first RFID tag overa shared connection, such as the signal line 1382 in FIG. 18. In oneembodiment, the second message may also include an error detection code.Once the second message with the tag identification of the second RFIDtag is received by the first RFID tag of the connected RFID tags, thefirst RFID tag will check to see if the tag identification was correctlyreceived. In one embodiment, an error detection code sent in the secondmessage may be used to determine if the tag identification of the secondRFID tag was correctly received by the first RFID tag. If the tagidentification was correctly received, the first RFID tag will send anacknowledgement to the second mated RFID tag to indicate that the tagidentification was correctly received (block 1406). If the tagidentification was not correctly received (i.e., an acknowledgement isnot received), then the tag identification may be retransmitted up to acertain number of times. If the tag identification is not correctlyreceived after a certain number of retransmissions, an error code may beentered in a memory of the RFID tag and the process continues in oneembodiment. In another embodiment, the connected tag identification maybe deleted so that a mistake is not made by reading erroneousinformation by the RFID reader.

If the tag identifications of both the first and second RFID tags werecorrectly received, an indication of a successful tag identificationexchange may be provided to an RFID reader (block 1408). An RFID reader(such as the RFID reader 1330, FIG. 16) can poll either of the firstRFID tag or the second RFID tag to monitor whether or not an indicationof a successful tag identification exchange has been made. The RFIDreader 1330 may read the tag identification of any of the RFID tags andacknowledge successful receipt of any of the tag identifications.

Once a successful tag identification exchange has been made, the tagscan operate in any manner for which they are suited. A check isperiodically made to see if the tag is still connected (step 1410). Ifthe tag is still connected, the tag may perform typical tag operations(step 1412). This includes, but is not limited to, read and writeoperations to the RFID reader, as well as receiving and storing data. Ifthe tag is not still connected, then the operation goes back to thestart, and attempts to detect a connected tag.

The general protocol for the exchange of tag identifications between twoconnected RFID tags is described above in FIG. 20. However, the protocolin FIG. 20 is exemplary only and may include additional steps, or thesteps may be performed in a different order. For example, in oneembodiment, the steps shown in blocks 1400 and 1402 could be performedbefore the steps shown in blocks 1404 and 1406. In another embodiment,the steps shown in blocks 1404 and 1406 could be performed before thesteps shown in blocks 1400 and 1402. The first RFID tag may receive thetag identification from the second RFID tag and send an acknowledgement(blocks 1404 and 1406) before the first RFID tag sends its tagidentification to the second RFID tag and receives an acknowledgementfrom the second RFID tag (blocks 1400 and 1402).

Further, if an acknowledgement is not received in block 1402, then theRFID tag may retransmit any tag identification transmitted with an error(i.e., it has not been acknowledged as received correctly), as discussedin more detail below with respect to FIGS. 21A-21C.

In addition, the sending of the first tag identification from the firstRFID tag to the second RFID tag and the receipt of the acknowledgementfrom the second RFID tag (blocks 1400 and 1402) can occur substantiallyat the same time as the receiving of the second tag identification fromthe second RFID tag and the sending of an acknowledgement to the secondRFID tag if the communications channel is full duplex. In oneembodiment, the communications channel is full duplex if two or moresignal lines exist between the connected RFID tags are used, each of thesignal lines being unidirectional (as seen below in FIG. 23). Forpurposes of this embodiment, “substantially at the same time” means thateither of the sending of the first tag identification from the firstRFID tag to the second RFID tag and the receipt of the acknowledgementfrom the second RFID tag (blocks 1400 and 1402) may overlap in time withthe receiving of the second tag identification from the second RFID tagand/or the sending of an acknowledgement to the second RFID tag.

FIGS. 21A-21C comprise a flowchart illustrating an exemplary protocolfor communicating between a plurality of connected RFID tags showingvarious steps of the protocol in response to different conditions. Theexemplary protocol of FIGS. 21A-21C is from the perspective of one RFIDtag in a set of potentially connected RFID tags. The protocol starts atblock 1414. A first RFID tag checks its signal/ground lines to see ifthere is a connected RFID tag (block 1416). If the first RFID tag is notconnected to a second RFID tag (block 1418), then appropriate disconnectprocessing is performed at block 1419 and the process returns to block1416 and the signal/ground lines are checked again to see if there is aconnected RFID tag. If the first RFID tag is connected to a second RFIDtagat block 1418, the first RFID tag performs one or more of threeactions depending on the state of various conditions. These threeactions may be done concurrently, as indicated by the horizontal blackbar in FIG. 21A. The first action, as shown in the left branch, is thatthe connection status of the tag is monitored (step 1420). If adisconnect is detected between the RFID tags, then at block 1422, thefirst RFID tag goes back to block 1416 and continues to check itssignal/ground lines to see if there is a connected and mated RFID tag.If a disconnect is not detected, the connection status of the tag isperiodically monitored for a disconnect.

A second potential concurrent action, as shown by the middle branch Band FIG. 21B, is that the first RFID tag will send its tagidentification to the second mated RFID tag if the tag identificationhas not been previously sent to the second mated RFID tag andacknowledged (block 1424). The first RFID tag will then wait for anacknowledgement from the second RFID tag that the tag identification wasreceived by the second RFID tag. As discussed above with respect to FIG.20, in one embodiment, the tag identification may be sent along with anerror detection code. If the error detection code sent in the firstmessage indicates that the tag identification of the first RFID tag wascorrectly received by the second RFID tag, then the second RFID tag willsend an acknowledgement to the first RFID tag that the tagidentification was correctly received. If the error detection code sentin the first message indicates that the tag identification of the firstRFID tag was not correctly received by the second RFID tag, or if anacknowledgement is not received from the second RFID tag, then the tagidentification is resent until a successful transmission of the tagidentification is achieved or until a certain number of unsuccessfultries are attempted (block 1426).

The connection status of the RFID tags is checked and a connection stateis stored in the RFID tag memory for access by the RFID reader (block1428). In one embodiment, a state indicating the connection status ofthe first RFID tag may be stored in a memory (such as memory 1326 or1328, FIG. 16), where it may be accessed later by the first RFID tag,another RFID tag, or an RFID reader (such as the RFID reader 1330, FIG.16). Upon storing of the information in tag memory, whether thetransmission of the second tag identification from the second RFID tagto the first RFID tag was successful or not, the first RFID tagcontinues to check its signal/ground lines to see if it is connected toa mated RFID tag other than the second RFID tag.

The third potential concurrent action that may occur in the protocolillustrated in FIGS. 21A-21C, as shown by the right branch C and FIG.21C, is that the first RFID tag may receive a second tag identificationfrom the second RFID tag to which the first RFID tag is connected (block1430). Upon receipt of the second tag identification from the secondRFID tag, the first RFID tag will check to see if the second tagidentification has been received correctly. This may involve checking anerror detection code received along with the second tag identificationfrom the second RFID tag, as discussed above. The first RFID tag willsend an acknowledgement of receipt to the second RFID tag if the secondtag identification was correctly received (block 1430). The first RFIDtag will send a message requesting retransmission of the second tagidentification if the second tag identification was not correctlyreceived or to continue if unsuccessful after a certain number of tries(block 1432). The connection status of the RFID tags is checked and aconnection state and the connected tag identification is stored in theRFID tag memory for access by the RFID reader (block 1434). In oneembodiment, a state indicating the connection status of the first RFIDtag, as well as the connected tag identification, may be stored in amemory (such as memory 1326 or 1328, FIG. 16), where it may be accessedlater by the first RFID tag, another RFID tag, or an RFID reader (suchas the RFID reader 1330, FIG. 16) (block 1434). Upon storing of theinformation in tag memory, whether the transmission of the second tagidentification from the second RFID tag to the first RFID tag wassuccessful or not, the first RFID tag returns to monitor thesignal/ground lines to determine if the first RFID tag is stillconnected to the second RFID tag.

With any of the exemplary protocols illustrated in FIG. 20 and FIGS.21A-21C, there are a variety of physical mechanisms that can be used totransfer information between connected RFID tags.

Voltage Sensing

One approach for communicating digital signals between mated RFID tagsis to generate a voltage signal on the transmitting side and to sense avoltage level on the receiving side. In order to discriminate between adigital “1” or “0” signal level, a unique voltage threshold range isassigned for both a low signal and a high signal. Typically names suchas Vih and Vil (Voltage input high and Voltage input low) are used todefine the range of input voltages for sensing a “1” and a “0” signal,respectively. Similarly, the names Voh and Vol (Voltage output high andVoltage output low) are used to specify the valid output voltage rangesfor a “1” and a “0” signal, respectively. Note that in order to preventa signal from being misinterpreted when at the boundary between a “1”and a “0” signal, a deadband range is inherently created between Vol maxand Voh min in which it is invalid to transmit a signal to ensure thatit is interpreted correctly at the receiving end.

Current Mode Sensing

An alternate approach for communicating digital signals between matedRFID tags is current mode sensing. Two concerns with using a voltagesensing mechanism are a) RFID tags operate with low power and lowvoltages, therefore the deadband range between Vol max and Voh min isnecessarily smaller than with, for instance, a 5V Transistor-TransistorLogic (TTL) signal, and b) the RFID operating environment is typicallyan “electronically noisy” environment in which noise can easily becoupled onto these low power, low voltage signals. This combination ofreduced deadband and noisy signal environment makes current sensing aviable alternative. This current sensing approach is very similar to thevoltage sensing approach, having similar threshold ranges (Iih→Currentinput high, Iil→Current input low, Ioh→Current output high, Iol→Currentoutput low) for a “0” vs. a “1” signal. The voltage sensing approach andthe current mode sensing approach each has advantages and theappropriate mechanism should be chosen for the specific applicationconditions such as noise immunity, signal bit rate, power efficiency,and the like.

Separate Communication Lines for Each Tag

In another alternate embodiment, there is a separate physical connectionfor each of the RFID tags 1312, 1316 (see FIG. 23) to utilize fortransmitting its tag identification, thus allowing one or more of theRFID tags 1312 and/or 1316 to continuously (or regularly) transmit itstag identification. This embodiment would allow each of the mated RFIDtags 1312, 1316 to continuously listen to the other end of the separatephysical connection to see if the particular RFID tag 1312 or 1316 hasbeen connected and what the associated tag identification is. In thisapproach, the RFID tag may have to operate in an extremely low powerenvironment since the RFID tag must harvest enough power from the RFenergy from a nearby RFID reader's transmissions in order to poweritself. This low power requirement also necessitates a very small diesize. Because of these constraints, it is not desirable to “waste power”by continuously transmitting information that has already been capturedby one of the mated RFID tags 1312 and 1316.

Shared Line

Another alternate approach to saving power might be to shrink die sizeby sharing a common physical connection, such as the common line 1380 inFIG. 18 between the RFID tags 1312, 1316 for both the transmit andreceive signals (rather than having a separate line for both transmitand receive). For this embodiment, there would need to be some type ofprotocol initiation method that the RFID tags 1312, 1316 utilize toinitiate the transfer of tag identifications. For instance, the RFIDtags 1312, 1316 could wait for a communication from the RFID reader 1330before sending a request transmission to the other one of RFID tag 1312or 1316 for it to send its tag identification so that it is ready “justin time” for the request from the RFID reader 1330. This would be areader directed synchronization method. Another method of protocolinitiation is to assign one of the RFID tags as a master and the otheras slave in each of the RFID tags 1312, 1316, with this assignment beingdone at the time of manufacture such that the slave RFID tag alwayswaits for the master RFID tag to initiate the start of the mating tagidentification communications. In a system where there is to becommunication between one or more RFID tags and/or one or more devices,one or more of the devices may also act as a master that initiates theexchange of information.

Another alternate approach for protocol initiation would be to utilize arandom back off time before transmitting along with a collisiondetection mechanism (similar to the Carrier-Sense MultipleAccess/Collision Detection (CSMA/CD) protocol used by Ethernet (IEEE802.3).

Multiplex

Several of these same techniques could also be utilized for the casewhere more than two RFID tags are connected together (i.e., three ormore RFID tags are connected together). An alternate approach specificto the multi-tag scenario utilizes separate transmit and receiveconnections in a “token passing” type protocol. In one embodiment, theRFID tags could form a ring where each RFID tag's transmit is connectedto the next RFID tag's receive. This approach could utilize themaster/slave property to control the protocol initiation. Once theprotocol is initiated, the communication works around the ring until itis completed.

Error Checking

Again, because the RFID tags could be operating in a noisy environmentutilizing low power communication mechanisms, some type of errorchecking/correction mechanism may be utilized in these tag-to-tagcommunications. One exemplary technique is to append a cyclic redundancycheck (CRC) or parity bit or bits on the end of the tag identification,combined with a retransmit protocol. If the RFID tags were to be used ina very noisy environment, other well-known error detection and/orcorrection methods could be employed, such as, but not limited to,forward error correction (FEC) techniques.

There are several fault conditions and cases that must be considered inthe tag-to-tag communications. Using error detection (such as the CRC)may handle the case where an RFID tag powers down before completing thetag-to-tag communication since the receiving end will detect an error inthe transmission. There are several other subtle fault conditions thatneed more careful consideration. If an RFID tag is mated and already hascommunicated its tag identification and then is powered off, it could bepossible to disconnect this RFID tag and replace it with another beforeit is powered up again. Upon power up, to ensure that thedisconnect/reconnect event is guaranteed to be detected and handledproperly, a maximum power off time allowed before the mating tagidentification is considered to be invalid may be specified. If themaximum power off time is reached, the tag identification must be readagain. An alternate approach would be to provide a disconnectiondetection mechanism that immediately invalidates the stored mating tagidentification upon detection of a physical disconnection (even underthe conditions of no tag power.

Varying power conditions and RF noise will be factors in the reliabilityof the tag-to-tag communications and the potential need for associatedre-transmission. The reliability of the tag-to-tag transfer willnaturally increase as the number of bits transferred is reduced (i.e.,this reduces the transfer time as well). For some applications withsmaller populations of RFID tags, it is not necessary to transfer thetotal number of bits of the tag identification (which may be up toninety-six (96) bits in one embodiment). In one embodiment, only aportion of a total number of bits in the first tag identification needsto be sent from the first RFID tag and received by the second RFID tagin order to generate an indication that the first tag identification wascorrectly received by the second RFID tag.

In one embodiment, the number of bits needed is related to the number ofRFID tags that could be seen simultaneously by the RFID reader.Depending on the application, a parameter could be set in each RFID tag(i.e., in a memory of the RFID tag, such as memory 1326 or 1328 in FIG.16) which controls the number of bits of the tag identification to betransferred. This would provide a configurable mechanism to balance thenumber of potential RFID tags in the RFID reader's field with the amountof time required to transfer the tag identification (which is directlyrelated to the transfer reliability).

In addition to the basic point-to-point configuration illustrated inFIG. 18, other configurations of two or more mated RFID tags may utilizethe protocols disclosed above in FIG. 20 and FIGS. 21A-21C. FIG. 22shows two RFID tags in an alternative point-to-point configuration. Notethat although FIG. 22 is discussed with respect to RFID tag 1312 andRFID tag 1316, the RFID tags 1312 and 1316 could be positioned on adevice. In addition, a device that emulates an RFID tag could be used inplace of RFID tags 1312 and 1316. In one embodiment, a device 1312 and adevice 1316 could be used in the place of RFID tag 1312 and RFID tag1316 and the two devices can communicate with each other in the samemanner as the RFID tag 1312 and the RFID tag 1316 communicate with eachother, as described in more detail below.

FIG. 22 is similar to FIG. 18, in that the two RFID tags 1312, 1316 areconnected by the common line 1380. The two RFID tags 1312, 1316 may beconnected to each other via a variety of means (including but notlimited to ohmic, inductive, and capacitive connections). The embodimentof FIG. 22 differs from the embodiment of FIG. 18 in that the RFID tags1312, 1316 are connected by two signal lines 1382A and 1382B. Each ofthe signal lines 1382A and 1382B are unidirectional, with the signalline 1382A configured to carry signals left to right from the RFID tag1312 to the RFID tag 1316, and the signal line 1382B configured to carrysignals right to left from the RFID tag 1316 to the RFID tag 1312. Ashared bidirectional line may offer economy of hardware (ports, circuittraces, etc.) but may require more sophisticated electronics andprotocols. The alternate embodiment having two unidirectional signallines may utilize simpler electronics, but may use more costlyinterconnect hardware. In the embodiment of FIG. 22, the RFID tags 1312,1316 may utilize the protocols disclosed above in FIG. 20 and FIGS.21A-21C.

FIGS. 23-26 show some representative multiple tag topologies forconnecting more than two RFID tags. FIG. 23 is an exemplary chainconfiguration in which a plurality of RFID tags may be connected to eachother. Note that although FIG. 22 is discussed with respect to RFID tag1312, RFID tag 1316, and RFID tag 1440, one or more of the RFID tags1312, 1316, and 1440 could be positioned on a device. In addition, adevice that emulates an RFID tag could be used in place of RFID tags1312, 1316 and/or 1440. For example, in one embodiment, a device 1312and a device 1316 could be used in the place of RFID tag 1312 and RFIDtag 1316 and the two devices can communicate with each other in the samemanner as the RFID tag 1312 and the RFID tag 1316 communicate with eachother, as described in more detail below. In another embodiment, therecould be two RFID tags, like RFID tags 1312 and 1316, and a device couldbe used in the place of RFID tag 1440 such that there are two RFID tagsin a point-to-point configuration with a device 1440. This embodimentmay be referred to as a “relay” configuration, where information may becommunicated, or relayed from RFID tag 1312 to RFID tag 1316 and thencommunicated, or relayed, from RFID tag 1316 to RFID tag or device 1440.

In the embodiment of FIG. 23, a plurality of n RFID tags are connectedto each other in a daisy chain configuration, in which the RFID tag 1312is connected to the RFID tag 1316 via the common line 1380 and thesignal line 1382. RFID tag 1316 is also connected to another RFID tag(not shown) in the chain via a common line 1380-2 and a signal line1382-2. Any number n of RFID tags may be connected until the last RFIDtag in the chain (RFID tag 1440 in the embodiment of FIG. 23) isconnected to the previous RFID tag in the chain via a common line 1380-nand a signal line 1382-n. Each of the signal lines 1382, 1382-2, and1382-n may be a shared bidirectional signal line. However, in alternateembodiments, any or all of the RFID tags in the chain may have twounidirectional signal lines (as shown in FIG. 22) in place of the singlebidirectional signal line.

In the embodiment of FIG. 23, each of the RFID tags in the chain mayutilize the protocols disclosed above in FIG. 20 and FIGS. 21A-21C tocommunicate with the RFID tag or tags to which it is connected in thechain. In this manner, data, information, and signals may becommunicated from any one of the RFID tags in the chain configuration toany other one of the RFID tags in the chain configuration. For example,in the embodiment of FIG. 23, the RFID tag 1312 may communicate directlywith the RFID tag 1316, and the RFID tag 1316 may communicate directlywith the next RFID tag in the chain, and so on, until a signal, data, orother information is communicated from the RFID tag 1312 all the way tothe RFID tag 1440.

FIG. 24 is an exemplary ring configuration in which a plurality of RFIDtags may be connected to each other. Note that although FIG. 24 isdiscussed with respect to RFID tag 1312, RFID tag 1316, RFID tag 1442,and RFID tag 1444, one or more of the RFID tags 1312, 1316, 1442, and1444 could be positioned on a device. In addition, a device thatemulates an RFID tag could be used in place of RFID tags 1312, 1316,1442 and/or 1444. For example, in one embodiment, a device 1312 and adevice 1316 could be used in the place of RFID tag 1312 and RFID tag1316 and the two devices can communicate with each other in the samemanner as the RFID tag 1312 and the RFID tag 1316 communicate with eachother, as described in more detail below. In another embodiment, therecould be two RFID tags, like RFID tags 1312 and 1316, and two devicescould be used in the place of RFID tags 1442 and 1444 such that thereare two RFID tags in a point-to-point configuration with two devices1442 and 1444. This embodiment may be referred to as a “ring”configuration.

In the embodiment of FIG. 24, a plurality of n RFID tags and/or devicesare connected to each other in a ring configuration, in which the RFIDtag 1312 is connected to the RFID tag 1316 via the common line 1380 andthe signal line 1382. The RFID tag 1312 is also connected to an RFID tag1442 in the ring via a common line 1380-3 and a signal line 1382-3. TheRFID tag 1442 is connected to an RFID tag 1444 in the ring via a commonline 80-4 and a signal line 82-4. The RFID tag 16 is connected to theRFID tag 1444 in the ring via a common line 1380-n and a signal line1382-n. Although four RFID tags are explicitly shown in FIG. 24, anynumber n of RFID tags may be connected in the ring. Each of the signallines 1382, 1382-3, 1382-4, and 1382-n may be a shared bidirectionalsignal line. However, in alternate embodiments, any or all of the RFIDtags in the chain may have two unidirectional signal lines (as shown inFIG. 23) in place of the single bidirectional signal line.

In the embodiment of FIG. 24, the RFID tags 1312, 1316, 1442, and 1444may utilize the protocols disclosed above in FIG. 20 and FIGS. 21A-21Cto communicate with any of the other RFID tags in the ring. In thismanner, data, information, and signals may be communicated from any oneof the RFID tags in the ring configuration to any other one of the RFIDtags in the ring. For example, in the embodiment of FIG. 24, the RFIDtag 1312 may communicate directly with the RFID tag 1316, and the RFIDtag 1316 may communicate directly with the RFID tag 1444. The RFID tagmay communicate directly with the RFID tag 1442, which may in turncommunicate directly with the RFID tag 1312. In this manner, a signal,data, or other information may be communicated from the RFID tag 1312 tothe RFID tag 1444, or vice versa.

FIG. 25 is an exemplary bus configuration in which a plurality of RFIDtags may be connected to each other. In this embodiment, a plurality ofn RFID tags are connected to each other in a bus configuration, in whicheach of the RFID tags are connected to each other via a commoncommunications bus 1450. Thus, in FIG. 25, each of the RFID tags 1312,1316, 1446, and 1448 are connected to the common communications bus 1450via their respective bus interfaces 1452-1, 1452-2, 1452-3, and 1452-4.The connection to the communications bus 1450 can use a ground line pluseither a single bidirectional signal line or two unidirectional signallines, to communicate to and from the communications bus 1450. Althoughfour RFID tags are explicitly shown in FIG. 24, any number n of RFIDtags may be connected via n number of bus interfaces to the commoncommunications bus 1450.

In the embodiment of FIG. 25, the RFID tags 1312, 1316, 1446, and 1448may utilize the protocols disclosed above in FIG. 20 and FIGS. 21A-21Cto communicate with any of the other RFID tags in the bus configuration.In this manner, data, information, and signals may be communicated fromany one of the RFID tags in the bus configuration to any other one ofthe RFID tags connected to the common communications bus 1450. Forexample, in the embodiment of FIG. 25, the RFID tag 1312 may communicatea signal, data, or other information via its bus interface 1452-1 to thecommon communications bus 1450, where it may then be sent simultaneouslyto any and all of the other RFID tags 1316, 1446, and 1448. In thismanner, a signal, data, or other information may be communicated betweenany of the RFID tags connected to the common communications bus 1450.

Note that although FIG. 25 is discussed with respect to RFID tag 1312,RFID tag 1316, RFID tag 1446, and RFID tag 1448, one or more of the RFIDtags 1312, 1316, 1446, and 1448 could be positioned on a device. Inaddition, a device that emulates an RFID tag could be used in place ofRFID tags 1312, 1316, 1446, and 1448.

FIG. 26 is an exemplary star configuration in which a plurality of RFIDtags may be connected to each other. In this embodiment, a plurality ofn RFID tags are connected to each other in a star configuration, inwhich the RFID tag 1312 is connected to each of the other RFID tags inthe star configuration. Thus, the RFID tag 1312 is connected to the RFIDtag 1316 via the common line 1380 and the signal line 1382. The RFID tag1312 is also connected to an RFID tag 1454 via a common line 1380-3 anda signal line 1382-3. The RFID tag 1312 is also connected to an RFID tag1456 via a common line 1380-4 and a signal line 1382-4. The RFID tag1312 is also connected to an RFID tag 1458 via a common line 1380-n anda signal line 1382-n. Although five RFID tags are explicitly shown inFIG. 26, any number n of RFID tags may be connected to the central RFIDtag 1312 in the star configuration. Each of the signal lines 1382,1382-3, 1382-4, and 1382-n may be a shared bidirectional signal line.However, in alternate embodiments, any or all of the RFID tags in thechain may have two unidirectional signal lines (as shown in FIG. 22) inplace of the single bidirectional signal line.

In the embodiment of FIG. 26, the RFID tags 1312, 1316, 1454, 1456, and1458 may utilize the protocols disclosed above in FIG. 20 and FIGS.21A-21C to communicate with any of the other RFID tags in the starconfiguration. In this manner, data, information, and signals may becommunicated from any one of the RFID tags in the star configuration toany other one of the RFID tags in the star configuration. For example,in the embodiment of FIG. 26, the RFID tag 1312 may communicate directlywith each of the other RFID tags 1316, 1454, 1456, and 1458. Forexample, the RFID tag 1316 may communicate a signal, data, or otherinformation to the RFID tag 1312 via the signal line 1382, where it maythen be sent to any of the other RFID tags 1454, 1456, and 1458 via therespective signal lines 1382-3, 1382-4, and 1382-n. In this manner, asignal, data, or other information may be communicated between any ofthe RFID tags in the star configuration.

Note that although FIG. 25 is discussed with respect to RFID tag 1312,RFID tag 1316, RFID tag 1454, RFID tag 1456, and RFID tag 1458, one ormore of the RFID tags 1312, 1316, 1454, 1456, and 1458 could bepositioned on a device. In addition, a device that emulates an RFID tagcould be used in place of RFID tags 1312, 1316, 1454, 1456, and 1448.

By employing the disclosed protocols and related systems and methods,RFID tag-to-tag connectivity can be determined without the need toburden the RFID reader with extensive communication between two or moreRFID tags. Once the connectivity of two or more mated RFID tags isestablished, the two or more mated RFID tags can communicate with eachother using direct connections between the RFID tags. In this manner,the two or more mated RFID tags may send a signal, data, or otherinformation between connected RFID tags.

Any functionalities disclosed in any embodiments may be incorporated orprovided in any other embodiments with suitable circuitry and/ordevices. Although the illustrated embodiments are directed tocomponents, wherein RFID-enabled versions of the components, includingICs and IC chips, employ passive RFID tags, further embodiments includeone or more semi-passive or active RFID tags depending upon theparticular functionality of the RFID tag system desired.

Although the embodiments described herein are directed to RFID tags forcommunications, the embodiments are applicable to any type of component.Examples include fiber optic connectors and adapters or copperconnectors and adapters and other fiber optic and/or copper components.Embodiments disclosed herein can be used in non-telecommunicationsequipment, particularly regarding components that interconnect and/orare exposed to various conditions for which it is desirable to know thelocation, connectivity, and/or conditions of the components. Thetechnology described herein is applicable to any two items that need tobe mated with each other in a known way, such as electrical connectors,medical devices, fluid couplings, beverage dispensing containers,industrial controls, environmental monitoring devices, connection ofconsumer electronics, electronics assemblies and subassemblies,containers and lids, doors and doorframes, windows and sills, and manyother applications. The terms “plug” and “socket” are generally usedherein to define portions of components that are adapted for connectingto one another, such as a connector that is received by an adapter, andare not necessarily limited to standard plugs and sockets.

Further, as used herein, it is intended that terms “fiber optic cables”and/or “optical fibers” include all types of single mode and multi-modelight waveguides, including one or more optical fibers that may beupcoated, colored, buffered, ribbonized and/or have other organizing orprotective structure in a cable such as one or more tubes, strengthmembers, jackets or the like. Likewise, other types of suitable opticalfibers include bend-insensitive optical fibers, or any other expedientof a medium for transmitting light signals. An example of abend-insensitive, or bend resistant, optical fiber is ClearCurve®Multimode fiber commercially available from Corning Incorporated.Suitable fibers of this type are disclosed, for example, in U.S. PatentApplication Publication Nos. 2008/0166094 and 2009/0169163.

Many modifications and other embodiments of the embodiments set forthherein will come to mind to one skilled in the art to which theembodiments pertain having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the description and claims are not to be limited tothe specific embodiments disclosed and that modifications and otherembodiments are intended to be included within the scope of the appendedclaims. It is intended that the embodiments cover the modifications andvariations of the embodiments provided they come within the scope of theappended claims and their equivalents. Although specific terms areemployed herein, they are used in a generic and descriptive sense onlyand not for purposes of limitation.

What is claimed is:
 1. A method of communicating between a plurality ofradio frequency identification (RFID) tags, comprising: detecting aphysically mated electrical connection between a first RFID tag of theplurality of RFID tags and a second RFID tag of the plurality of RFIDtags; and after detecting the physically mated electrical connectionbetween the first RFID tag and the second RFID tag, directly exchanginginformation between the first RFID tag and the second RFID tag via thephysically mated electrical connection, wherein the physically matedelectrical connection comprises a direct contact between a firstelectrical lead of the first RFID tag and a second electrical lead ofthe second RFID tag.
 2. The method of claim 1, further comprising:sending a first message comprising a first tag identification directlyfrom the first RFID tag to the second RFID tag.
 3. The method of claim2, further comprising receiving a first acknowledgement from the secondRFID tag at the first RFID tag if the first tag identification wascorrectly received by the second RFID tag.
 4. The method of claim 3,further comprising resending the first tag identification if the firstacknowledgement is not received by the second RFID tag.
 5. The method ofclaim 3, wherein the first tag identification comprises an errordetection code, the method further comprising checking the errordetection code prior to sending the first acknowledgement.
 6. The methodof claim 3 further comprising receiving the first acknowledgment over asignal line that is shared between the first and second RFID tags. 7.The method of claim 2, further comprising sending a second messagecomprising a second tag identification directly from the second RFID tagto the first RFID tag.
 8. The method of claim 7, further comprisingreceiving a second acknowledgement from the first RFID tag at the secondRFID tag if the second tag identification was correctly received by thefirst RFID tag.
 9. The method of claim 8, further comprising resendingthe second tag information if the second acknowledgement is not receivedby the first RFID tag.
 10. The method of claim 8, wherein the second tagidentification comprises an error detection code, the method furthercomprising checking the error detection code prior to sending the secondacknowledgement.
 11. The method of claim 8 further comprising receivingthe second acknowledgment over a signal line that is shared between thefirst and second RFID tags.
 12. The method of claim 8, wherein thesending of the first message and the receiving of the firstacknowledgment occurs at substantially the same time as the sending ofthe second message and the receiving of the second acknowledgement. 13.The method of claim 2, wherein the first tag identification is stored inmemory of the second RFID tag.
 14. The method of claim 2, wherein only aportion of a total number of bits in the first tag identification issent from the first RFID tag.
 15. The method of claim 14, wherein theportion of the total number of bits are received by the second RFID tagin order to generate an indication that the first tag identification wascorrectly received by the second RFID tag.
 16. The method of claim 14,wherein the portion of the total number of bits are received by thesecond RFID tag in order to indicate a type of component.
 17. The methodof claim 2, further comprising: sending a third message comprising thesecond tag identification directly from the second RFID tag to a thirdRFID tag of the plurality of RFID tags; and receiving a thirdacknowledgement from the third RFID tag at the second RFID tag if thesecond tag identification was correctly received by the third RFID tag.18. The method of claim 2, further comprising: sending a third messagecomprising the first tag identification directly from the second RFIDtag to a third RFID tag of the plurality of RFID tags; and receiving athird acknowledgement from the third RFID tag at the second RFID tag ifthe first tag identification was correctly received by the third RFIDtag.
 19. The method of claim 1, further comprising storing an indicationin memory of at least one of the first and second RFID tags, theindication indicative of a state of the physically mated electricalconnection between the first RFID tag and the second RFID tag.
 20. Themethod of claim 1 further comprising directly exchanging informationbetween the first and second RFID tags over a signal line that is sharedbetween the first and second RFID tags.
 21. The method of claim 1further comprising directly sending information over a firstunidirectional signal line from the first RFID tag to the second RFIDtag and directly sending information over a second unidirectional signalline from the second RFID tag to the first RFID tag.
 22. The method ofclaim 21 further comprising receiving the first acknowledgment at thefirst RFID tag from the second RFID tag over the second unidirectionalsignal line and receiving the second acknowledgement at the second RFIDtag from the first RFID tag over the first unidirectional signal line.23. The method of claim 1, wherein the information is stored in memoryof the second RFID tag.
 24. The method of claim 1, further comprisingdetecting a disconnect between the first RFID tag and the second RFIDtag.
 25. The method of claim 1, wherein the information exchangedbetween the first RFID tag and the second RFID tag comprises one or moreof a signal, data, memory contents, register contents, statusinformation, and/or component data.
 26. The method of claim 1, furthercomprising using voltage sensing to communicate the signal, data, and/orinformation between the first RFID tag and the second RFID tag.
 27. Themethod of claim 1, further comprising using current sensing tocommunicate the signal, data, and/or information between the first RFIDtag and the second RFID tag.
 28. The method of claim 1, wherein at leastone of the first RFID tag and the second RFID tag is a passive RFID tag.29. The method of claim 28 further comprising powering one or more ofthe passive RFID tags by a RFID reader.
 30. The method of claim 28further comprising powering one or more of the passive RFID tags byexcess energy received through one or more antennas and stored in one ormore capacitors communicatively coupled to the first and/or second RFIDtags.
 31. A system for communicating between radio frequencyidentification (RFID) tags comprising: a first RFID tag; and a secondRFID tag, wherein the first and second RFID tags are configured to:physically mate electrically to each other; detect that a physicallymated electrical connection exists between the first RFID and the secondRFID tag; and after detecting the physically mated electrical connectionbetween the first RFID tag and the second RFID tag exists, directlyexchange information via the physically mated electrical connection,wherein the physically mated electrical connection comprises a directcontact between a first electrical lead of the first RFID tag and asecond electrical lead of the second RFID tag.
 32. The system of claim31, wherein the first RFID tag is further configured to send a firstmessage comprising a first tag identification directly from the firstRFID tag to the second RFID tag.
 33. The system of claim 32, wherein thefirst RFID tag is further configured to receive a first acknowledgementfrom the second RFID tag if the first tag identification was correctlyreceived by the second RFID tag.
 34. The system of claim 31, wherein thesecond RFID tag is further configured to send a second messagecomprising a second tag identification directly from the second RFID tagto the first RFID tag.
 35. The system of claim 34, wherein the secondRFID tag is further configured to receive a second acknowledgement fromthe first RFID tag if the second tag identification was correctlyreceived by the first RFID tag.
 36. The system of claim 31, wherein thefirst and second RFID tags are further configured to directly exchangeidentification information using a common protocol.
 37. The system ofclaim 31 wherein the first and second RFID tags are further configuredto directly exchange identification information without control from anRFID reader.
 38. The system of claim 31, wherein the first and secondRFID tags are connected in a point-to-point configuration.
 39. Thesystem of claim 31, wherein one of the first and second RFID tags is amaster tag that initiates the exchange of information.
 40. The system ofclaim 39, wherein the information is identification information.
 41. Thesystem of claim 31, wherein the first and second RFID tags are furtherconfigured to directly exchange identification information over a signalline that is shared between the first and second RFID tags.
 42. Thesystem of claim 31, wherein the first RFID tag is further configured todirectly send identification information over a first unidirectionalsignal line to the second RFID tag and the second RFID tag is furtherconfigured to directly send identification information over a secondunidirectional signal line to the first RFID tag.
 43. The system ofclaim 31, wherein the first and second RFID tags are connected via anohmic connection.
 44. The system of claim 31, wherein the first andsecond RFID tags are part of a plurality of connected RFID tags that areconnected in a chain configuration.
 45. The system of claim 31, whereinthe first and second RFID tags are part of a plurality of connected RFIDtags that are connected in a ring configuration.
 46. The system of claim31, wherein the first and second RFID tags are part of a plurality ofconnected RFID tags that are connected in a bus configuration comprisinga communications bus.
 47. The system of claim 31, wherein the first andsecond RFID tags are part of a plurality of connected RFID tags that areconnected in a star configuration.
 48. The system of claim 31, whereinat least one of the first RFID tag and the second RFID tag is a passiveRFID tag.
 49. The system of claim 48 further comprising one or morecapacitors communicatively coupled to one of the first and second RFIDtags and configured to store excess energy received through one or moreantennas for providing power to one of the first and second RFID tags.